21861215 has 8 divisors (see below), whose sum is σ = 27138240. Its totient is φ = 16885792.

The previous prime is 21861209. The next prime is 21861221. The reversal of 21861215 is 51216812.

It is an interprime number because it is at equal distance from previous prime (21861209) and next prime (21861221).

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

It is a cyclic number.

It is not a de Polignac number, because 21861215 - 2⁴ = 21861199 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 75239 + ... + 75528.

It is an arithmetic number, because the mean of its divisors is an integer number (3392280).

Almost surely, 2^21861215 is an apocalyptic number.

21861215 is a deficient number, since it is larger than the sum of its proper divisors (5277025).

21861215 is a wasteful number, since it uses less digits than its factorization.

21861215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 150801.

The product of its digits is 960, while the sum is 26.

The square root of 21861215 is about 4675.5978227388. The cubic root of 21861215 is about 279.6134760250.

The spelling of 21861215 in words is "twenty-one million, eight hundred sixty-one thousand, two hundred fifteen".