81351204237 has 6 divisors (see below), whose sum is σ = 117507295022. Its totient is φ = 54234136152.

The previous prime is 81351204211. The next prime is 81351204281. The reversal of 81351204237 is 73240215318.

81351204237 is a `hidden beast` number, since 81 + 35 + 120 + 423 + 7 = 666.

It can be written as a sum of positive squares in only one way, i.e., 79282228041 + 2068976196 = 281571^2 + 45486^2 .

It is not a de Polignac number, because 81351204237 - 2¹⁵ = 81351171469 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81351204287) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4519511338 + ... + 4519511355.

Almost surely, 2^81351204237 is an apocalyptic number.

It is an amenable number.

81351204237 is a deficient number, since it is larger than the sum of its proper divisors (36156090785).

81351204237 is a wasteful number, since it uses less digits than its factorization.

81351204237 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9039022699 (or 9039022696 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The spelling of 81351204237 in words is "eighty-one billion, three hundred fifty-one million, two hundred four thousand, two hundred thirty-seven".