72781117 has 2 divisors, whose sum is σ = 72781118. Its totient is φ = 72781116.

The previous prime is 72781103. The next prime is 72781129. The reversal of 72781117 is 71118727.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 44169316 + 28611801 = 6646^2 + 5349^2 .

It is a cyclic number.

It is not a de Polignac number, because 72781117 - 2⁷ = 72780989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (72781157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36390558 + 36390559.

It is an arithmetic number, because the mean of its divisors is an integer number (36390559).

Almost surely, 2^72781117 is an apocalyptic number.

It is an amenable number.

72781117 is a deficient number, since it is larger than the sum of its proper divisors (1).

72781117 is an equidigital number, since it uses as much as digits as its factorization.

72781117 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5488, while the sum is 34.

The square root of 72781117 is about 8531.1849704481. The cubic root of 72781117 is about 417.5157908139.

The spelling of 72781117 in words is "seventy-two million, seven hundred eighty-one thousand, one hundred seventeen".