21864331 has 8 divisors (see below), whose sum is σ = 22713344. Its totient is φ = 21024360.

The previous prime is 21864317. The next prime is 21864341. The reversal of 21864331 is 13346812.

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 21864331 - 2¹³ = 21856139 is a prime.

It is a super-2 number, since 2×21864331² = 956097940155122, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21864331.

It is not an unprimeable number, because it can be changed into a prime (21864301) 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, 2890 + ... + 7216.

It is an arithmetic number, because the mean of its divisors is an integer number (2839168).

Almost surely, 2^21864331 is an apocalyptic number.

21864331 is a deficient number, since it is larger than the sum of its proper divisors (849013).

21864331 is a wasteful number, since it uses less digits than its factorization.

21864331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4521.

The product of its digits is 3456, while the sum is 28.

The square root of 21864331 is about 4675.9310302869. The cubic root of 21864331 is about 279.6267603461.

The spelling of 21864331 in words is "twenty-one million, eight hundred sixty-four thousand, three hundred thirty-one".