21674557 has 2 divisors, whose sum is σ = 21674558. Its totient is φ = 21674556.

The previous prime is 21674551. The next prime is 21674561. The reversal of 21674557 is 75547612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11215801 + 10458756 = 3349^2 + 3234^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21674557 is a prime.

It is a super-2 number, since 2×21674557² = 939572842292498, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21674551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10837278 + 10837279.

It is an arithmetic number, because the mean of its divisors is an integer number (10837279).

Almost surely, 2^21674557 is an apocalyptic number.

It is an amenable number.

21674557 is a deficient number, since it is larger than the sum of its proper divisors (1).

21674557 is an equidigital number, since it uses as much as digits as its factorization.

21674557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 58800, while the sum is 37.

The square root of 21674557 is about 4655.5941618659. The cubic root of 21674557 is about 278.8153906931.

It can be divided in two parts, 2167 and 4557, that added together give a square (6724 = 82²).

The spelling of 21674557 in words is "twenty-one million, six hundred seventy-four thousand, five hundred fifty-seven".