21120913 has 12 divisors (see below), whose sum is σ = 24440080. Its totient is φ = 18188280.

The previous prime is 21120901. The next prime is 21120929. The reversal of 21120913 is 31902112.

It is not a de Polignac number, because 21120913 - 2²¹ = 19023761 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is not an unprimeable number, because it can be changed into a prime (21120713) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2295 + ... + 6892.

Almost surely, 2^21120913 is an apocalyptic number.

It is an amenable number.

21120913 is a deficient number, since it is larger than the sum of its proper divisors (3319167).

21120913 is a wasteful number, since it uses less digits than its factorization.

21120913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9228 (or 9217 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 19.

The square root of 21120913 is about 4595.7494492194. The cubic root of 21120913 is about 276.4209122342.

The spelling of 21120913 in words is "twenty-one million, one hundred twenty thousand, nine hundred thirteen".