20120640 has 56 divisors (see below), whose sum is σ = 63886080. Its totient is φ = 5365248.

The previous prime is 20120629. The next prime is 20120641. The reversal of 20120640 is 4602102.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is not an unprimeable number, because it can be changed into a prime (20120641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9520 + ... + 11439.

Almost surely, 2^20120640 is an apocalyptic number.

20120640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20120640 is an abundant number, since it is smaller than the sum of its proper divisors (43765440).

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

20120640 is a wasteful number, since it uses less digits than its factorization.

20120640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20979 (or 20969 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 20120640 is about 4485.6036383078. The cubic root of 20120640 is about 271.9864468449.

Adding to 20120640 its reverse (4602102), we get a palindrome (24722742).

It can be divided in two parts, 201 and 20640, that multiplied together give a triangular number (4148640 = T₂₈₈₀).

The spelling of 20120640 in words is "twenty million, one hundred twenty thousand, six hundred forty".