21351868 has 6 divisors (see below), whose sum is σ = 37365776. Its totient is φ = 10675932.

The previous prime is 21351829. The next prime is 21351893. The reversal of 21351868 is 86815312.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2668980 + ... + 2668987.

Almost surely, 2^21351868 is an apocalyptic number.

It is an amenable number.

21351868 is a deficient number, since it is larger than the sum of its proper divisors (16013908).

21351868 is a wasteful number, since it uses less digits than its factorization.

21351868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5337971 (or 5337969 counting only the distinct ones).

The product of its digits is 11520, while the sum is 34.

The square root of 21351868 is about 4620.8081544249. The cubic root of 21351868 is about 277.4248066161.

The spelling of 21351868 in words is "twenty-one million, three hundred fifty-one thousand, eight hundred sixty-eight".