21242679 has 4 divisors (see below), whose sum is σ = 28323576. Its totient is φ = 14161784.

The previous prime is 21242659. The next prime is 21242681. The reversal of 21242679 is 97624212.

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 21242679 - 2¹¹ = 21240631 is a prime.

It is a super-2 number, since 2×21242679² = 902502822194082, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21242629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3540444 + ... + 3540449.

It is an arithmetic number, because the mean of its divisors is an integer number (7080894).

Almost surely, 2^21242679 is an apocalyptic number.

21242679 is a deficient number, since it is larger than the sum of its proper divisors (7080897).

21242679 is an equidigital number, since it uses as much as digits as its factorization.

21242679 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7080896.

The product of its digits is 12096, while the sum is 33.

The square root of 21242679 is about 4608.9780863007. The cubic root of 21242679 is about 276.9511006837.

The spelling of 21242679 in words is "twenty-one million, two hundred forty-two thousand, six hundred seventy-nine".