72781231 has 2 divisors, whose sum is σ = 72781232. Its totient is φ = 72781230.

The previous prime is 72781207. The next prime is 72781237. The reversal of 72781231 is 13218727.

It is a strong prime.

It is an emirp because it is prime and its reverse (13218727) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 72781231 - 2⁷ = 72781103 is a prime.

It is a super-2 number, since 2×72781231² = 10594215171750722, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 72781193 and 72781202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (72781237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36390615 + 36390616.

It is an arithmetic number, because the mean of its divisors is an integer number (36390616).

Almost surely, 2^72781231 is an apocalyptic number.

72781231 is a deficient number, since it is larger than the sum of its proper divisors (1).

72781231 is an equidigital number, since it uses as much as digits as its factorization.

72781231 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4704, while the sum is 31.

The square root of 72781231 is about 8531.1916518151. The cubic root of 72781231 is about 417.5160088044.

Adding to 72781231 its reverse (13218727), we get a palindrome (85999958).

The spelling of 72781231 in words is "seventy-two million, seven hundred eighty-one thousand, two hundred thirty-one".