1231687157 has 2 divisors, whose sum is σ = 1231687158. Its totient is φ = 1231687156.

The previous prime is 1231687153. The next prime is 1231687181. The reversal of 1231687157 is 7517861321.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1187078116 + 44609041 = 34454^2 + 6679^2 .

It is an emirp because it is prime and its reverse (7517861321) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1231687157 - 2² = 1231687153 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1231687151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615843578 + 615843579.

It is an arithmetic number, because the mean of its divisors is an integer number (615843579).

Almost surely, 2^1231687157 is an apocalyptic number.

It is an amenable number.

1231687157 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231687157 is an equidigital number, since it uses as much as digits as its factorization.

1231687157 is an evil number, because the sum of its binary digits is even.

The product of its digits is 70560, while the sum is 41.

The square root of 1231687157 is about 35095.4007955458. The cubic root of 1231687157 is about 1071.9309346632.

The spelling of 1231687157 in words is "one billion, two hundred thirty-one million, six hundred eighty-seven thousand, one hundred fifty-seven".