20151640 has 16 divisors (see below), whose sum is σ = 45341280. Its totient is φ = 8060640.

The previous prime is 20151619. The next prime is 20151667. The reversal of 20151640 is 4615102.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 251856 + ... + 251935.

It is an arithmetic number, because the mean of its divisors is an integer number (2833830).

Almost surely, 2^20151640 is an apocalyptic number.

20151640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20151640 is an abundant number, since it is smaller than the sum of its proper divisors (25189640).

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

20151640 is a wasteful number, since it uses less digits than its factorization.

20151640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 503802 (or 503798 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 20151640 is about 4489.0578076028. The cubic root of 20151640 is about 272.1260589274.

Adding to 20151640 its reverse (4615102), we get a palindrome (24766742).

It can be divided in two parts, 2015 and 1640, that added together give a triangular number (3655 = T₈₅).

The spelling of 20151640 in words is "twenty million, one hundred fifty-one thousand, six hundred forty".