21689520 has 40 divisors (see below), whose sum is σ = 67238256. Its totient is φ = 5783808.

The previous prime is 21689509. The next prime is 21689527. The reversal of 21689520 is 2598612.

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

It is not an unprimeable number, because it can be changed into a prime (21689527) 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, 44947 + ... + 45426.

Almost surely, 2^21689520 is an apocalyptic number.

21689520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21689520 is an abundant number, since it is smaller than the sum of its proper divisors (45548736).

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

21689520 is a wasteful number, since it uses less digits than its factorization.

21689520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90389 (or 90383 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 21689520 is about 4657.2008760628. The cubic root of 21689520 is about 278.8795358724.

The spelling of 21689520 in words is "twenty-one million, six hundred eighty-nine thousand, five hundred twenty".