21275939 has 4 divisors (see below), whose sum is σ = 21354720. Its totient is φ = 21197160.

The previous prime is 21275909. The next prime is 21275941. The reversal of 21275939 is 93957212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21275939 - 2¹² = 21271843 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21275909) 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, 38984 + ... + 39525.

It is an arithmetic number, because the mean of its divisors is an integer number (5338680).

Almost surely, 2^21275939 is an apocalyptic number.

21275939 is a deficient number, since it is larger than the sum of its proper divisors (78781).

21275939 is an equidigital number, since it uses as much as digits as its factorization.

21275939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78780.

The product of its digits is 34020, while the sum is 38.

The square root of 21275939 is about 4612.5848501681. The cubic root of 21275939 is about 277.0955675580.

The spelling of 21275939 in words is "twenty-one million, two hundred seventy-five thousand, nine hundred thirty-nine".