72135257 has 4 divisors (see below), whose sum is σ = 72153780. Its totient is φ = 72116736.

The previous prime is 72135253. The next prime is 72135269. The reversal of 72135257 is 75253127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 75253127 = 67 ⋅1123181.

It can be written as a sum of positive squares in 2 ways, for example, as 9709456 + 62425801 = 3116^2 + 7901^2 .

It is a cyclic number.

It is not a de Polignac number, because 72135257 - 2² = 72135253 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72135251) 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, 908 + ... + 12045.

It is an arithmetic number, because the mean of its divisors is an integer number (18038445).

Almost surely, 2^72135257 is an apocalyptic number.

It is an amenable number.

72135257 is a deficient number, since it is larger than the sum of its proper divisors (18523).

72135257 is a wasteful number, since it uses less digits than its factorization.

72135257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18522.

The product of its digits is 14700, while the sum is 32.

The square root of 72135257 is about 8493.2477298145. The cubic root of 72135257 is about 416.2771071153.

The spelling of 72135257 in words is "seventy-two million, one hundred thirty-five thousand, two hundred fifty-seven".