21479779 has 2 divisors, whose sum is σ = 21479780. Its totient is φ = 21479778.

The previous prime is 21479767. The next prime is 21479839. The reversal of 21479779 is 97797412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21479779 - 2¹⁵ = 21447011 is a prime.

It is a super-2 number, since 2×21479779² = 922761811777682, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21479729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10739889 + 10739890.

It is an arithmetic number, because the mean of its divisors is an integer number (10739890).

Almost surely, 2^21479779 is an apocalyptic number.

21479779 is a deficient number, since it is larger than the sum of its proper divisors (1).

21479779 is an equidigital number, since it uses as much as digits as its factorization.

21479779 is an evil number, because the sum of its binary digits is even.

The product of its digits is 222264, while the sum is 46.

The square root of 21479779 is about 4634.6282483064. The cubic root of 21479779 is about 277.9776865620.

The spelling of 21479779 in words is "twenty-one million, four hundred seventy-nine thousand, seven hundred seventy-nine".