21315258 has 16 divisors (see below), whose sum is σ = 47367360. Its totient is φ = 7105068.

The previous prime is 21315253. The next prime is 21315269. The reversal of 21315258 is 85251312.

It is a happy number.

21315258 is a `hidden beast` number, since 2 + 131 + 525 + 8 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21315251) 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, 197310 + ... + 197417.

It is an arithmetic number, because the mean of its divisors is an integer number (2960460).

Almost surely, 2^21315258 is an apocalyptic number.

21315258 is an abundant number, since it is smaller than the sum of its proper divisors (26052102).

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

21315258 is a wasteful number, since it uses less digits than its factorization.

21315258 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 394738 (or 394732 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

The square root of 21315258 is about 4616.8450266389. The cubic root of 21315258 is about 277.2661580065.

The spelling of 21315258 in words is "twenty-one million, three hundred fifteen thousand, two hundred fifty-eight".