72170857 has 4 divisors (see below), whose sum is σ = 78731856. Its totient is φ = 65609860.

The previous prime is 72170851. The next prime is 72170893. The reversal of 72170857 is 75807127.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 75807127 = 11 ⋅6891557.

It is a cyclic number.

It is not a de Polignac number, because 72170857 - 2¹¹ = 72168809 is a prime.

It is a super-2 number, since 2×72170857² = 10417265200228898, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72170851) 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, 3280483 + ... + 3280504.

It is an arithmetic number, because the mean of its divisors is an integer number (19682964).

Almost surely, 2^72170857 is an apocalyptic number.

It is an amenable number.

72170857 is a deficient number, since it is larger than the sum of its proper divisors (6560999).

72170857 is a wasteful number, since it uses less digits than its factorization.

72170857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6560998.

The product of its (nonzero) digits is 27440, while the sum is 37.

The square root of 72170857 is about 8495.3432538068. The cubic root of 72170857 is about 416.3455758430.

The spelling of 72170857 in words is "seventy-two million, one hundred seventy thousand, eight hundred fifty-seven".