81651237093 has 24 divisors (see below), whose sum is σ = 118462944600. Its totient is φ = 54193434624.

The previous prime is 81651237053. The next prime is 81651237113. The reversal of 81651237093 is 39073215618.

81651237093 is a `hidden beast` number, since 8 + 16 + 512 + 37 + 0 + 93 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 1506759489 + 80144477604 = 38817^2 + 283098^2 .

It is not a de Polignac number, because 81651237093 - 2⁶ = 81651237029 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81651237023) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3200773 + ... + 3226181.

It is an arithmetic number, because the mean of its divisors is an integer number (4935956025).

Almost surely, 2^81651237093 is an apocalyptic number.

It is an amenable number.

81651237093 is a deficient number, since it is larger than the sum of its proper divisors (36811707507).

81651237093 is a wasteful number, since it uses less digits than its factorization.

81651237093 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26981 (or 26978 counting only the distinct ones).

The product of its (nonzero) digits is 272160, while the sum is 45.

The spelling of 81651237093 in words is "eighty-one billion, six hundred fifty-one million, two hundred thirty-seven thousand, ninety-three".