1557166109 has 4 divisors (see below), whose sum is σ = 1639122240. Its totient is φ = 1475209980.

The previous prime is 1557166097. The next prime is 1557166141. The reversal of 1557166109 is 9016617551.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9016617551 = 397 ⋅22711883.

It is a cyclic number.

It is not a de Polignac number, because 1557166109 - 2⁸ = 1557165853 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1557166159) 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, 40978037 + ... + 40978074.

It is an arithmetic number, because the mean of its divisors is an integer number (409780560).

Almost surely, 2^1557166109 is an apocalyptic number.

1557166109 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

1557166109 is a deficient number, since it is larger than the sum of its proper divisors (81956131).

1557166109 is an equidigital number, since it uses as much as digits as its factorization.

1557166109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81956130.

The product of its (nonzero) digits is 56700, while the sum is 41.

The square root of 1557166109 is about 39460.9440966635. The cubic root of 1557166109 is about 1159.0752908462.

The spelling of 1557166109 in words is "one billion, five hundred fifty-seven million, one hundred sixty-six thousand, one hundred nine".