21258881 has 4 divisors (see below), whose sum is σ = 24295872. Its totient is φ = 18221892.

The previous prime is 21258871. The next prime is 21258907. The reversal of 21258881 is 18885212.

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 not a de Polignac number, because 21258881 - 2⁶ = 21258817 is a prime.

It is a super-2 number, since 2×21258881² = 903880042744322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21258871) 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, 1518485 + ... + 1518498.

It is an arithmetic number, because the mean of its divisors is an integer number (6073968).

Almost surely, 2^21258881 is an apocalyptic number.

It is an amenable number.

21258881 is a deficient number, since it is larger than the sum of its proper divisors (3036991).

21258881 is an equidigital number, since it uses as much as digits as its factorization.

21258881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3036990.

The product of its digits is 10240, while the sum is 35.

The square root of 21258881 is about 4610.7354077197. The cubic root of 21258881 is about 277.0214938988.

The spelling of 21258881 in words is "twenty-one million, two hundred fifty-eight thousand, eight hundred eighty-one".