72557557 has 4 divisors (see below), whose sum is σ = 72726336. Its totient is φ = 72388780.

The previous prime is 72557549. The next prime is 72557587. The reversal of 72557557 is 75575527.

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: 75575527 = 8089 ⋅9343.

It is a cyclic number.

It is not a de Polignac number, because 72557557 - 2³ = 72557549 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72557587) 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, 83743 + ... + 84604.

It is an arithmetic number, because the mean of its divisors is an integer number (18181584).

Almost surely, 2^72557557 is an apocalyptic number.

It is an amenable number.

72557557 is a deficient number, since it is larger than the sum of its proper divisors (168779).

72557557 is a wasteful number, since it uses less digits than its factorization.

72557557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 168778.

The product of its digits is 428750, while the sum is 43.

The square root of 72557557 is about 8518.0723758372. The cubic root of 72557557 is about 417.0878613025.

It can be divided in two parts, 72 and 557557, that multiplied together give a palindrome (40144104).

The spelling of 72557557 in words is "seventy-two million, five hundred fifty-seven thousand, five hundred fifty-seven".