21641520 has 40 divisors (see below), whose sum is σ = 67089456. Its totient is φ = 5771008.

The previous prime is 21641509. The next prime is 21641537. The reversal of 21641520 is 2514612.

It is a tau number, because it is divible by the number of its divisors (40).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44847 + ... + 45326.

Almost surely, 2^21641520 is an apocalyptic number.

21641520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21641520 is an abundant number, since it is smaller than the sum of its proper divisors (45447936).

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

21641520 is a wasteful number, since it uses less digits than its factorization.

21641520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90189 (or 90183 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 21641520 is about 4652.0447117370. The cubic root of 21641520 is about 278.6736591069.

The spelling of 21641520 in words is "twenty-one million, six hundred forty-one thousand, five hundred twenty".