72133561 has 4 divisors (see below), whose sum is σ = 72550692. Its totient is φ = 71716432.

The previous prime is 72133553. The next prime is 72133573. The reversal of 72133561 is 16533127.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 62173225 + 9960336 = 7885^2 + 3156^2 .

It is a cyclic number.

It is not a de Polignac number, because 72133561 - 2³ = 72133553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72133541) 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, 208306 + ... + 208651.

It is an arithmetic number, because the mean of its divisors is an integer number (18137673).

Almost surely, 2^72133561 is an apocalyptic number.

It is an amenable number.

72133561 is a deficient number, since it is larger than the sum of its proper divisors (417131).

72133561 is a wasteful number, since it uses less digits than its factorization.

72133561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 417130.

The product of its digits is 3780, while the sum is 28.

The square root of 72133561 is about 8493.1478852072. The cubic root of 72133561 is about 416.2738446723.

Adding to 72133561 its reverse (16533127), we get a palindrome (88666688).

The spelling of 72133561 in words is "seventy-two million, one hundred thirty-three thousand, five hundred sixty-one".