16521640 has 32 divisors (see below), whose sum is σ = 39132000. Its totient is φ = 6260544.

The previous prime is 16521623. The next prime is 16521641. The reversal of 16521640 is 4612561.

16521640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (16521641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10110 + ... + 11629.

It is an arithmetic number, because the mean of its divisors is an integer number (1222875).

Almost surely, 2^16521640 is an apocalyptic number.

16521640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

16521640 is an abundant number, since it is smaller than the sum of its proper divisors (22610360).

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

16521640 is a wasteful number, since it uses less digits than its factorization.

16521640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21769 (or 21765 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 16521640 is about 4064.6820293843. The cubic root of 16521640 is about 254.6934159866.

It can be divided in two parts, 16521 and 640, that added together give a square (17161 = 131²).

The spelling of 16521640 in words is "sixteen million, five hundred twenty-one thousand, six hundred forty".