21864881 has 4 divisors (see below), whose sum is σ = 22815552. Its totient is φ = 20914212.

The previous prime is 21864859. The next prime is 21864883. The reversal of 21864881 is 18846812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21864881 is a prime.

It is a super-2 number, since 2×21864881² = 956146042288322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21864883) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 475301 + ... + 475346.

It is an arithmetic number, because the mean of its divisors is an integer number (5703888).

Almost surely, 2^21864881 is an apocalyptic number.

It is an amenable number.

21864881 is a deficient number, since it is larger than the sum of its proper divisors (950671).

21864881 is an equidigital number, since it uses as much as digits as its factorization.

21864881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 950670.

The product of its digits is 24576, while the sum is 38.

The square root of 21864881 is about 4675.9898417340. The cubic root of 21864881 is about 279.6291050086.

The spelling of 21864881 in words is "twenty-one million, eight hundred sixty-four thousand, eight hundred eighty-one".