20139840 has 336 divisors, whose sum is σ = 84319872. Its totient is φ = 4478976.

The previous prime is 20139793. The next prime is 20139851. The reversal of 20139840 is 4893102.

It is a tau number, because it is divible by the number of its divisors (336).

It is a super-2 number, since 2×20139840² = 811226310451200, which contains 22 as substring.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 544302 + ... + 544338.

It is an arithmetic number, because the mean of its divisors is an integer number (250952).

Almost surely, 2^20139840 is an apocalyptic number.

20139840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20139840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42159936).

20139840 is an abundant number, since it is smaller than the sum of its proper divisors (64180032).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20139840 is an equidigital number, since it uses as much as digits as its factorization.

20139840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76 (or 54 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 20139840 is about 4487.7433081673. The cubic root of 20139840 is about 272.0729331527.

The spelling of 20139840 in words is "twenty million, one hundred thirty-nine thousand, eight hundred forty".