21221515436 has 24 divisors (see below), whose sum is σ = 40523056896. Its totient is φ = 9643939920.

The previous prime is 21221515433. The next prime is 21221515453. The reversal of 21221515436 is 63451512212.

It is not an unprimeable number, because it can be changed into a prime (21221515433) 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, 148145 + ... + 253751.

It is an arithmetic number, because the mean of its divisors is an integer number (1688460704).

Almost surely, 2^21221515436 is an apocalyptic number.

It is an amenable number.

21221515436 is a deficient number, since it is larger than the sum of its proper divisors (19301541460).

21221515436 is a wasteful number, since it uses less digits than its factorization.

21221515436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110189 (or 110187 counting only the distinct ones).

The product of its digits is 14400, while the sum is 32.

The spelling of 21221515436 in words is "twenty-one billion, two hundred twenty-one million, five hundred fifteen thousand, four hundred thirty-six".