72017731 has 4 divisors (see below), whose sum is σ = 72040072. Its totient is φ = 71995392.

The previous prime is 72017711. The next prime is 72017773. The reversal of 72017731 is 13771027.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-72017731 is a prime.

It is a super-2 number, since 2×72017731² = 10373107156776722, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 72017731.

It is not an unprimeable number, because it can be changed into a prime (72017711) 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 3 ways as a sum of consecutive naturals, for example, 5310 + ... + 13123.

It is an arithmetic number, because the mean of its divisors is an integer number (18010018).

Almost surely, 2^72017731 is an apocalyptic number.

72017731 is a deficient number, since it is larger than the sum of its proper divisors (22341).

72017731 is a wasteful number, since it uses less digits than its factorization.

72017731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22340.

The product of its (nonzero) digits is 2058, while the sum is 28.

The square root of 72017731 is about 8486.3261191166. The cubic root of 72017731 is about 416.0509117762.

Adding to 72017731 its reverse (13771027), we get a palindrome (85788758).

The spelling of 72017731 in words is "seventy-two million, seventeen thousand, seven hundred thirty-one".