21864455 has 8 divisors (see below), whose sum is σ = 27083904. Its totient is φ = 16927200.

The previous prime is 21864443. The next prime is 21864457. The reversal of 21864455 is 55446812.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21864455 - 2¹⁸ = 21602311 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21864457) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 70376 + ... + 70685.

It is an arithmetic number, because the mean of its divisors is an integer number (3385488).

Almost surely, 2^21864455 is an apocalyptic number.

21864455 is a deficient number, since it is larger than the sum of its proper divisors (5219449).

21864455 is a wasteful number, since it uses less digits than its factorization.

21864455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 141097.

The product of its digits is 38400, while the sum is 35.

The square root of 21864455 is about 4675.9442896596. The cubic root of 21864455 is about 279.6272889644.

The spelling of 21864455 in words is "twenty-one million, eight hundred sixty-four thousand, four hundred fifty-five".