21421079 has 6 divisors (see below), whose sum is σ = 21634704. Its totient is φ = 21209540.

The previous prime is 21421061. The next prime is 21421091. The reversal of 21421079 is 97012412.

It is a de Polignac number, because none of the positive numbers 2^k-21421079 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21421679) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 10514 + ... + 12384.

It is an arithmetic number, because the mean of its divisors is an integer number (3605784).

Almost surely, 2^21421079 is an apocalyptic number.

21421079 is a deficient number, since it is larger than the sum of its proper divisors (213625).

21421079 is an equidigital number, since it uses as much as digits as its factorization.

21421079 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2085 (or 1978 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 21421079 is about 4628.2911533308. The cubic root of 21421079 is about 277.7242361457.

The spelling of 21421079 in words is "twenty-one million, four hundred twenty-one thousand, seventy-nine".