81572739761541 has 32 divisors (see below), whose sum is σ = 125409993477120. Its totient is φ = 46197297748224.

The previous prime is 81572739761533. The next prime is 81572739761543. The reversal of 81572739761541 is 14516793727518.

It is not a de Polignac number, because 81572739761541 - 2³ = 81572739761533 is a prime.

It is a super-2 number, since 2×81572739761541² (a number of 29 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81572739761543) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 33377770 + ... + 35738228.

It is an arithmetic number, because the mean of its divisors is an integer number (3919062296160).

Almost surely, 2^{81572739761541} is an apocalyptic number.

It is an amenable number.

81572739761541 is a deficient number, since it is larger than the sum of its proper divisors (43837253715579).

81572739761541 is a wasteful number, since it uses less digits than its factorization.

81572739761541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2375145.

The product of its digits is 88905600, while the sum is 66.

The spelling of 81572739761541 in words is "eighty-one trillion, five hundred seventy-two billion, seven hundred thirty-nine million, seven hundred sixty-one thousand, five hundred forty-one".