21515408812 has 24 divisors (see below), whose sum is σ = 37808942976. Its totient is φ = 10712898048.

The previous prime is 21515408779. The next prime is 21515408839. The reversal of 21515408812 is 21880451512.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2514213 + ... + 2522755.

It is an arithmetic number, because the mean of its divisors is an integer number (1575372624).

Almost surely, 2^21515408812 is an apocalyptic number.

It is an amenable number.

21515408812 is a deficient number, since it is larger than the sum of its proper divisors (16293534164).

21515408812 is a wasteful number, since it uses less digits than its factorization.

21515408812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11097 (or 11095 counting only the distinct ones).

The product of its (nonzero) digits is 25600, while the sum is 37.

The spelling of 21515408812 in words is "twenty-one billion, five hundred fifteen million, four hundred eight thousand, eight hundred twelve".