1291872157 has 4 divisors (see below), whose sum is σ = 1323381276. Its totient is φ = 1260363040.

The previous prime is 1291872133. The next prime is 1291872163. The reversal of 1291872157 is 7512781921.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 77070841 + 1214801316 = 8779^2 + 34854^2 .

It is a cyclic number.

It is not a de Polignac number, because 1291872157 - 2²³ = 1283483549 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 (1291872107) 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, 15754498 + ... + 15754579.

It is an arithmetic number, because the mean of its divisors is an integer number (330845319).

Almost surely, 2^1291872157 is an apocalyptic number.

It is an amenable number.

1291872157 is a deficient number, since it is larger than the sum of its proper divisors (31509119).

1291872157 is an equidigital number, since it uses as much as digits as its factorization.

1291872157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31509118.

The product of its digits is 70560, while the sum is 43.

The square root of 1291872157 is about 35942.6231235284. The cubic root of 1291872157 is about 1089.1135954928.

The spelling of 1291872157 in words is "one billion, two hundred ninety-one million, eight hundred seventy-two thousand, one hundred fifty-seven".