1557428991 has 8 divisors (see below), whose sum is σ = 2079135744. Its totient is φ = 1037004120.

The previous prime is 1557428981. The next prime is 1557429023. The reversal of 1557428991 is 1998247551.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1557428991 - 2⁶ = 1557428927 is a prime.

It is a super-3 number, since 3×1557428991³ (a number of 29 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1557428981) 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, 317631 + ... + 322496.

It is an arithmetic number, because the mean of its divisors is an integer number (259891968).

Almost surely, 2^1557428991 is an apocalyptic number.

1557428991 is a deficient number, since it is larger than the sum of its proper divisors (521706753).

1557428991 is an equidigital number, since it uses as much as digits as its factorization.

1557428991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 640941.

The product of its digits is 907200, while the sum is 51.

The square root of 1557428991 is about 39464.2748698111. The cubic root of 1557428991 is about 1159.1405125083.

The spelling of 1557428991 in words is "one billion, five hundred fifty-seven million, four hundred twenty-eight thousand, nine hundred ninety-one".