1557997531 has 2 divisors, whose sum is σ = 1557997532. Its totient is φ = 1557997530.

The previous prime is 1557997477. The next prime is 1557997561. The reversal of 1557997531 is 1357997551.

It is a strong prime.

It is an emirp because it is prime and its reverse (1357997551) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1557997531 - 2⁷ = 1557997403 is a prime.

It is a super-2 number, since 2×1557997531² = 4854712613204191922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1557997561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 778998765 + 778998766.

It is an arithmetic number, because the mean of its divisors is an integer number (778998766).

Almost surely, 2^1557997531 is an apocalyptic number.

1557997531 is a deficient number, since it is larger than the sum of its proper divisors (1).

1557997531 is an equidigital number, since it uses as much as digits as its factorization.

1557997531 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1488375, while the sum is 52.

The square root of 1557997531 is about 39471.4774362450. The cubic root of 1557997531 is about 1159.2815435656.

The spelling of 1557997531 in words is "one billion, five hundred fifty-seven million, nine hundred ninety-seven thousand, five hundred thirty-one".