21182921 has 16 divisors (see below), whose sum is σ = 22462848. Its totient is φ = 19958400.

The previous prime is 21182899. The next prime is 21182927. The reversal of 21182921 is 12928112.

It is a cyclic number.

It is not a de Polignac number, because 21182921 - 2⁶ = 21182857 is a prime.

It is a super-2 number, since 2×21182921² = 897432284184482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21182927) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 290141 + ... + 290213.

It is an arithmetic number, because the mean of its divisors is an integer number (1403928).

Almost surely, 2^21182921 is an apocalyptic number.

It is an amenable number.

21182921 is a deficient number, since it is larger than the sum of its proper divisors (1279927).

21182921 is an equidigital number, since it uses as much as digits as its factorization.

21182921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 272.

The product of its digits is 576, while the sum is 26.

The square root of 21182921 is about 4602.4907387196. The cubic root of 21182921 is about 276.6911587808.

The spelling of 21182921 in words is "twenty-one million, one hundred eighty-two thousand, nine hundred twenty-one".