1291640157 has 12 divisors (see below), whose sum is σ = 1900905084. Its totient is φ = 844846080.

The previous prime is 1291640143. The next prime is 1291640167. The reversal of 1291640157 is 7510461921.

1291640157 is a `hidden beast` number, since 1 + 2 + 9 + 1 + 640 + 1 + 5 + 7 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 549949401 + 741690756 = 23451^2 + 27234^2 .

It is not a de Polignac number, because 1291640157 - 2⁸ = 1291639901 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1291640167) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1353444 + ... + 1354397.

It is an arithmetic number, because the mean of its divisors is an integer number (158408757).

Almost surely, 2^1291640157 is an apocalyptic number.

It is an amenable number.

1291640157 is a deficient number, since it is larger than the sum of its proper divisors (609264927).

1291640157 is a wasteful number, since it uses less digits than its factorization.

1291640157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2707900 (or 2707897 counting only the distinct ones).

The product of its (nonzero) digits is 15120, while the sum is 36.

The square root of 1291640157 is about 35939.3956126143. The cubic root of 1291640157 is about 1089.0483956768.

The spelling of 1291640157 in words is "one billion, two hundred ninety-one million, six hundred forty thousand, one hundred fifty-seven".