21218692 has 12 divisors (see below), whose sum is σ = 40508496. Its totient is φ = 9644840.

The previous prime is 21218657. The next prime is 21218693. The reversal of 21218692 is 29681212.

It is not an unprimeable number, because it can be changed into a prime (21218693) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 241078 + ... + 241165.

It is an arithmetic number, because the mean of its divisors is an integer number (3375708).

Almost surely, 2^21218692 is an apocalyptic number.

21218692 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21218692 is a deficient number, since it is larger than the sum of its proper divisors (19289804).

21218692 is a wasteful number, since it uses less digits than its factorization.

21218692 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 482258 (or 482256 counting only the distinct ones).

The product of its digits is 3456, while the sum is 31.

The square root of 21218692 is about 4606.3751475537. The cubic root of 21218692 is about 276.8468180411.

Subtracting from 21218692 its product of digits (3456), we obtain a square (21215236 = 4606²).

The spelling of 21218692 in words is "twenty-one million, two hundred eighteen thousand, six hundred ninety-two".