21520920 has 64 divisors (see below), whose sum is σ = 67968000. Its totient is φ = 5436288.

The previous prime is 21520907. The next prime is 21520931. The reversal of 21520920 is 2902512.

It is a zygodrome in base 9.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2440 + ... + 6999.

It is an arithmetic number, because the mean of its divisors is an integer number (1062000).

Almost surely, 2^21520920 is an apocalyptic number.

21520920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21520920 is an abundant number, since it is smaller than the sum of its proper divisors (46447080).

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

21520920 is a wasteful number, since it uses less digits than its factorization.

21520920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9472 (or 9468 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 21.

The square root of 21520920 is about 4639.0645608786. The cubic root of 21520920 is about 278.1550469579.

The spelling of 21520920 in words is "twenty-one million, five hundred twenty thousand, nine hundred twenty".