997770157 has 4 divisors (see below), whose sum is σ = 1024736956. Its totient is φ = 970803360.

The previous prime is 997770139. The next prime is 997770173. The reversal of 997770157 is 751077799.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 751077799 = 17 ⋅44181047.

It can be written as a sum of positive squares in 2 ways, for example, as 699655401 + 298114756 = 26451^2 + 17266^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-997770157 is a prime.

It is the 31588-th Hogben number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (997770197) by changing a digit.

It is a nontrivial repunit in base 31587.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13483344 + ... + 13483417.

It is an arithmetic number, because the mean of its divisors is an integer number (256184239).

Almost surely, 2^997770157 is an apocalyptic number.

It is an amenable number.

997770157 is a deficient number, since it is larger than the sum of its proper divisors (26966799).

997770157 is a wasteful number, since it uses less digits than its factorization.

997770157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26966798.

The product of its (nonzero) digits is 972405, while the sum is 52.

The square root of 997770157 is about 31587.5000118718. The cubic root of 997770157 is about 999.2561658479.

The spelling of 997770157 in words is "nine hundred ninety-seven million, seven hundred seventy thousand, one hundred fifty-seven".