1557697397 has 8 divisors (see below), whose sum is σ = 1565246040. Its totient is φ = 1550165760.

The previous prime is 1557697319. The next prime is 1557697399. The reversal of 1557697397 is 7937967551.

It can be written as a sum of positive squares in 4 ways, for example, as 19018321 + 1538679076 = 4361^2 + 39226^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 1557697397 - 2¹⁰ = 1557696373 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1557697399) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 203129 + ... + 210657.

It is an arithmetic number, because the mean of its divisors is an integer number (195655755).

Almost surely, 2^1557697397 is an apocalyptic number.

It is an amenable number.

1557697397 is a deficient number, since it is larger than the sum of its proper divisors (7548643).

1557697397 is an equidigital number, since it uses as much as digits as its factorization.

1557697397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8503.

The product of its digits is 12502350, while the sum is 59.

The square root of 1557697397 is about 39467.6753432477. The cubic root of 1557697397 is about 1159.2070971165.

The spelling of 1557697397 in words is "one billion, five hundred fifty-seven million, six hundred ninety-seven thousand, three hundred ninety-seven".