73131721 has 8 divisors (see below), whose sum is σ = 80886344. Its totient is φ = 65681280.

The previous prime is 73131701. The next prime is 73131727. The reversal of 73131721 is 12713137.

It can be written as a sum of positive squares in 4 ways, for example, as 17106496 + 56025225 = 4136^2 + 7485^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 73131721 - 2¹⁷ = 73000649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (73131727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 75540 + ... + 76501.

It is an arithmetic number, because the mean of its divisors is an integer number (10110793).

Almost surely, 2^73131721 is an apocalyptic number.

It is an amenable number.

73131721 is a deficient number, since it is larger than the sum of its proper divisors (7754623).

73131721 is a wasteful number, since it uses less digits than its factorization.

73131721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 152091.

The product of its digits is 882, while the sum is 25.

The square root of 73131721 is about 8551.7086596773. The cubic root of 73131721 is about 418.1851415371.

Adding to 73131721 its reverse (12713137), we get a palindrome (85844858).

The spelling of 73131721 in words is "seventy-three million, one hundred thirty-one thousand, seven hundred twenty-one".