21155312 has 40 divisors (see below), whose sum is σ = 42507696. Its totient is φ = 10192896.

The previous prime is 21155287. The next prime is 21155339. The reversal of 21155312 is 21355112.

It is a happy number.

It is a congruent number.

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, 66578 + ... + 66894.

Almost surely, 2^21155312 is an apocalyptic number.

It is an amenable number.

21155312 is an abundant number, since it is smaller than the sum of its proper divisors (21352384).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21155312 is a wasteful number, since it uses less digits than its factorization.

21155312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 465 (or 459 counting only the distinct ones).

The product of its digits is 300, while the sum is 20.

The square root of 21155312 is about 4599.4904065559. The cubic root of 21155312 is about 276.5708969989.

The spelling of 21155312 in words is "twenty-one million, one hundred fifty-five thousand, three hundred twelve".