1557997551 has 16 divisors (see below), whose sum is σ = 2517976320. Its totient is φ = 944240760.

The previous prime is 1557997531. The next prime is 1557997561.

It is a happy number.

1557997551 is a `hidden beast` number, since 15 + 5 + 79 + 9 + 7 + 551 = 666.

1557997551 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1557997551 - 2⁷ = 1557997423 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1557997531) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2622595 + ... + 2623188.

It is an arithmetic number, because the mean of its divisors is an integer number (157373520).

Almost surely, 2^1557997551 is an apocalyptic number.

1557997551 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1557997551 is a deficient number, since it is larger than the sum of its proper divisors (959978769).

1557997551 is a wasteful number, since it uses less digits than its factorization.

1557997551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5245803 (or 5245797 counting only the distinct ones).

The product of its digits is 2480625, while the sum is 54.

The square root of 1557997551 is about 39471.4776895925. The cubic root of 1557997551 is about 1159.2815485262.

The spelling of 1557997551 in words is "one billion, five hundred fifty-seven million, nine hundred ninety-seven thousand, five hundred fifty-one".