1231722157 has 2 divisors, whose sum is σ = 1231722158. Its totient is φ = 1231722156.

The previous prime is 1231722103. The next prime is 1231722181. The reversal of 1231722157 is 7512271321.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1198613641 + 33108516 = 34621^2 + 5754^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1231722157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1231722257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615861078 + 615861079.

It is an arithmetic number, because the mean of its divisors is an integer number (615861079).

Almost surely, 2^1231722157 is an apocalyptic number.

It is an amenable number.

1231722157 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231722157 is an equidigital number, since it uses as much as digits as its factorization.

1231722157 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5880, while the sum is 31.

The square root of 1231722157 is about 35095.8994328397. The cubic root of 1231722157 is about 1071.9410880064.

Adding to 1231722157 its reverse (7512271321), we get a palindrome (8743993478).

The spelling of 1231722157 in words is "one billion, two hundred thirty-one million, seven hundred twenty-two thousand, one hundred fifty-seven".