21315393 has 40 divisors (see below), whose sum is σ = 35544960. Its totient is φ = 12618720.

The previous prime is 21315391. The next prime is 21315421. The reversal of 21315393 is 39351312.

It is a happy number.

It is not a de Polignac number, because 21315393 - 2¹ = 21315391 is a prime.

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 (21315391) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 41623 + ... + 42131.

It is an arithmetic number, because the mean of its divisors is an integer number (888624).

Almost surely, 2^21315393 is an apocalyptic number.

It is an amenable number.

21315393 is a deficient number, since it is larger than the sum of its proper divisors (14229567).

21315393 is a wasteful number, since it uses less digits than its factorization.

21315393 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 579 (or 570 counting only the distinct ones).

The product of its digits is 2430, while the sum is 27.

The square root of 21315393 is about 4616.8596469895. The cubic root of 21315393 is about 277.2667433595.

The spelling of 21315393 in words is "twenty-one million, three hundred fifteen thousand, three hundred ninety-three".