21312693 has 16 divisors (see below), whose sum is σ = 31664640. Its totient is φ = 14167872.

The previous prime is 21312677. The next prime is 21312721. The reversal of 21312693 is 39621312.

It is not a de Polignac number, because 21312693 - 2⁴ = 21312677 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21312673) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10780 + ... + 12602.

It is an arithmetic number, because the mean of its divisors is an integer number (1979040).

Almost surely, 2^21312693 is an apocalyptic number.

It is an amenable number.

21312693 is a deficient number, since it is larger than the sum of its proper divisors (10351947).

21312693 is a wasteful number, since it uses less digits than its factorization.

21312693 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2265 (or 2259 counting only the distinct ones).

The product of its digits is 1944, while the sum is 27.

The square root of 21312693 is about 4616.5672311795. The cubic root of 21312693 is about 277.2550358294.

The spelling of 21312693 in words is "twenty-one million, three hundred twelve thousand, six hundred ninety-three".