915721137 has 6 divisors (see below), whose sum is σ = 1322708322. Its totient is φ = 610480752.

The previous prime is 915721127. The next prime is 915721187. The reversal of 915721137 is 731127519.

It can be written as a sum of positive squares in only one way, i.e., 803382336 + 112338801 = 28344^2 + 10599^2 .

It is not a de Polignac number, because 915721137 - 2⁶ = 915721073 is a prime.

It is not an unprimeable number, because it can be changed into a prime (915721127) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 50873388 + ... + 50873405.

It is an arithmetic number, because the mean of its divisors is an integer number (220451387).

Almost surely, 2^915721137 is an apocalyptic number.

It is an amenable number.

915721137 is a deficient number, since it is larger than the sum of its proper divisors (406987185).

915721137 is a wasteful number, since it uses less digits than its factorization.

915721137 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101746799 (or 101746796 counting only the distinct ones).

The product of its digits is 13230, while the sum is 36.

The square root of 915721137 is about 30260.8846037256. The cubic root of 915721137 is about 971.0786657817.

The spelling of 915721137 in words is "nine hundred fifteen million, seven hundred twenty-one thousand, one hundred thirty-seven".