72188781 has 8 divisors (see below), whose sum is σ = 110001984. Its totient is φ = 41250720.

The previous prime is 72188777. The next prime is 72188819. The reversal of 72188781 is 18788127.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 72188781 - 2² = 72188777 is a prime.

It is a super-2 number, since 2×72188781² = 10422440204531922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72188761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1718760 + ... + 1718801.

It is an arithmetic number, because the mean of its divisors is an integer number (13750248).

Almost surely, 2^72188781 is an apocalyptic number.

It is an amenable number.

72188781 is a deficient number, since it is larger than the sum of its proper divisors (37813203).

72188781 is a wasteful number, since it uses less digits than its factorization.

72188781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3437571.

The product of its digits is 50176, while the sum is 42.

The square root of 72188781 is about 8496.3981192032. The cubic root of 72188781 is about 416.3800401716.

The spelling of 72188781 in words is "seventy-two million, one hundred eighty-eight thousand, seven hundred eighty-one".