21079557 has 6 divisors (see below), whose sum is σ = 30448262. Its totient is φ = 14053032.

The previous prime is 21079537. The next prime is 21079567. The reversal of 21079557 is 75597012.

It can be written as a sum of positive squares in only one way, i.e., 19793601 + 1285956 = 4449^2 + 1134^2 .

It is not a de Polignac number, because 21079557 - 2¹⁴ = 21063173 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 (21079537) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1171078 + ... + 1171095.

Almost surely, 2^21079557 is an apocalyptic number.

It is an amenable number.

21079557 is a deficient number, since it is larger than the sum of its proper divisors (9368705).

21079557 is a wasteful number, since it uses less digits than its factorization.

21079557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2342179 (or 2342176 counting only the distinct ones).

The product of its (nonzero) digits is 22050, while the sum is 36.

The square root of 21079557 is about 4591.2478695884. The cubic root of 21079557 is about 276.2403781720.

It can be divided in two parts, 2107 and 9557, that added together give a square (11664 = 108²).

The spelling of 21079557 in words is "twenty-one million, seventy-nine thousand, five hundred fifty-seven".