21312120028 has 24 divisors (see below), whose sum is σ = 38446682400. Its totient is φ = 10329496128.

The previous prime is 21312119993. The next prime is 21312120029. The reversal of 21312120028 is 82002121312.

It is a junction number, because it is equal to n+sod(n) for n = 21312119990 and 21312120008.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21312120029) 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, 227848 + ... + 307471.

It is an arithmetic number, because the mean of its divisors is an integer number (1601945100).

Almost surely, 2^21312120028 is an apocalyptic number.

It is an amenable number.

21312120028 is a deficient number, since it is larger than the sum of its proper divisors (17134562372).

21312120028 is a wasteful number, since it uses less digits than its factorization.

21312120028 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 535629 (or 535627 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 22.

The spelling of 21312120028 in words is "twenty-one billion, three hundred twelve million, one hundred twenty thousand, twenty-eight".