20439540 has 240 divisors, whose sum is σ = 74156544. Its totient is φ = 4665600.

The previous prime is 20439493. The next prime is 20439541. The reversal of 20439540 is 4593402.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20439541) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 552402 + ... + 552438.

Almost surely, 2^20439540 is an apocalyptic number.

20439540 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 20439540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37078272).

20439540 is an abundant number, since it is smaller than the sum of its proper divisors (53717004).

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

20439540 is a wasteful number, since it uses less digits than its factorization.

20439540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100 (or 89 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The square root of 20439540 is about 4521.0109488919. The cubic root of 20439540 is about 273.4158617870.

The spelling of 20439540 in words is "twenty million, four hundred thirty-nine thousand, five hundred forty".