21379775 has 6 divisors (see below), whose sum is σ = 26510952. Its totient is φ = 17103800.

The previous prime is 21379763. The next prime is 21379817. The reversal of 21379775 is 57797312.

It is not a de Polignac number, because 21379775 - 2⁴ = 21379759 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 427571 + ... + 427620.

It is an arithmetic number, because the mean of its divisors is an integer number (4418492).

Almost surely, 2^21379775 is an apocalyptic number.

21379775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21379775 is a deficient number, since it is larger than the sum of its proper divisors (5131177).

21379775 is an equidigital number, since it uses as much as digits as its factorization.

21379775 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 855201 (or 855196 counting only the distinct ones).

The product of its digits is 92610, while the sum is 41.

The square root of 21379775 is about 4623.8268782471. The cubic root of 21379775 is about 277.5456192079.

The spelling of 21379775 in words is "twenty-one million, three hundred seventy-nine thousand, seven hundred seventy-five".