557855721 has 8 divisors (see below), whose sum is σ = 826452960. Its totient is φ = 371903796.

The previous prime is 557855719. The next prime is 557855729. The reversal of 557855721 is 127558755.

557855721 is a `hidden beast` number, since 5 + 5 + 78 + 5 + 572 + 1 = 666.

It is not a de Polignac number, because 557855721 - 2¹ = 557855719 is a prime.

It is a super-2 number, since 2×557855721² = 622406010904859682, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (557855729) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10330635 + ... + 10330688.

It is an arithmetic number, because the mean of its divisors is an integer number (103306620).

Almost surely, 2^557855721 is an apocalyptic number.

It is an amenable number.

557855721 is a deficient number, since it is larger than the sum of its proper divisors (268597239).

557855721 is a wasteful number, since it uses less digits than its factorization.

557855721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20661332 (or 20661326 counting only the distinct ones).

The product of its digits is 490000, while the sum is 45.

The square root of 557855721 is about 23618.9695160479. The cubic root of 557855721 is about 823.2036684169.

The spelling of 557855721 in words is "five hundred fifty-seven million, eight hundred fifty-five thousand, seven hundred twenty-one".