21868406 has 36 divisors (see below), whose sum is σ = 39457908. Its totient is φ = 9062928.

The previous prime is 21868403. The next prime is 21868417. The reversal of 21868406 is 60486812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21868403) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 134081 + ... + 134243.

It is an arithmetic number, because the mean of its divisors is an integer number (1096053).

Almost surely, 2^21868406 is an apocalyptic number.

21868406 is a deficient number, since it is larger than the sum of its proper divisors (17589502).

21868406 is a wasteful number, since it uses less digits than its factorization.

21868406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 253 (or 209 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 35.

The square root of 21868406 is about 4676.3667520844. The cubic root of 21868406 is about 279.6441312300.

The spelling of 21868406 in words is "twenty-one million, eight hundred sixty-eight thousand, four hundred six".