21015112209 has 96 divisors (see below), whose sum is σ = 36293806080. Its totient is φ = 10714531968.

The previous prime is 21015112163. The next prime is 21015112219. The reversal of 21015112209 is 90221151012.

It is not a de Polignac number, because 21015112209 - 2⁷ = 21015112081 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21015112219) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 7453402 + ... + 7456220.

It is an arithmetic number, because the mean of its divisors is an integer number (378060480).

Almost surely, 2^21015112209 is an apocalyptic number.

It is an amenable number.

21015112209 is a deficient number, since it is larger than the sum of its proper divisors (15278693871).

21015112209 is a wasteful number, since it uses less digits than its factorization.

21015112209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2979 (or 2972 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 24.

The spelling of 21015112209 in words is "twenty-one billion, fifteen million, one hundred twelve thousand, two hundred nine".