21074557 has 6 divisors (see below), whose sum is σ = 24515358. Its totient is φ = 18063864.

The previous prime is 21074527. The next prime is 21074569. The reversal of 21074557 is 75547012.

It can be written as a sum of positive squares in only one way, i.e., 13351716 + 7722841 = 3654^2 + 2779^2 .

It is not a de Polignac number, because 21074557 - 2¹⁹ = 20550269 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21074527) 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, 214998 + ... + 215095.

It is an arithmetic number, because the mean of its divisors is an integer number (4085893).

Almost surely, 2^21074557 is an apocalyptic number.

It is an amenable number.

21074557 is a deficient number, since it is larger than the sum of its proper divisors (3440801).

21074557 is an equidigital number, since it uses as much as digits as its factorization.

21074557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 430107 (or 430100 counting only the distinct ones).

The product of its (nonzero) digits is 9800, while the sum is 31.

The square root of 21074557 is about 4590.7033230214. The cubic root of 21074557 is about 276.2185353488.

The spelling of 21074557 in words is "twenty-one million, seventy-four thousand, five hundred fifty-seven".