21868455 has 24 divisors (see below), whose sum is σ = 40703472. Its totient is φ = 9996672.

The previous prime is 21868447. The next prime is 21868459. The reversal of 21868455 is 55486812.

It is not a de Polignac number, because 21868455 - 2³ = 21868447 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21868459) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14142 + ... + 15611.

It is an arithmetic number, because the mean of its divisors is an integer number (1695978).

Almost surely, 2^21868455 is an apocalyptic number.

21868455 is a deficient number, since it is larger than the sum of its proper divisors (18835017).

21868455 is a wasteful number, since it uses less digits than its factorization.

21868455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29775 (or 29768 counting only the distinct ones).

The product of its digits is 76800, while the sum is 39.

The square root of 21868455 is about 4676.3719911915. The cubic root of 21868455 is about 279.6443400938.

The spelling of 21868455 in words is "twenty-one million, eight hundred sixty-eight thousand, four hundred fifty-five".