1557121457 has 4 divisors (see below), whose sum is σ = 1558516596. Its totient is φ = 1555726320.

The previous prime is 1557121439. The next prime is 1557121471. The reversal of 1557121457 is 7541217551.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 205750336 + 1351371121 = 14344^2 + 36761^2 .

It is a cyclic number.

It is not a de Polignac number, because 1557121457 - 2⁸ = 1557121201 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1557121457.

It is not an unprimeable number, because it can be changed into a prime (1557121427) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 695894 + ... + 698127.

It is an arithmetic number, because the mean of its divisors is an integer number (389629149).

Almost surely, 2^1557121457 is an apocalyptic number.

It is an amenable number.

1557121457 is a deficient number, since it is larger than the sum of its proper divisors (1395139).

1557121457 is a wasteful number, since it uses less digits than its factorization.

1557121457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1395138.

The product of its digits is 49000, while the sum is 38.

The square root of 1557121457 is about 39460.3783180040. The cubic root of 1557121457 is about 1159.0642118473.

The spelling of 1557121457 in words is "one billion, five hundred fifty-seven million, one hundred twenty-one thousand, four hundred fifty-seven".