81954940531 has 2 divisors, whose sum is σ = 81954940532. Its totient is φ = 81954940530.

The previous prime is 81954940519. The next prime is 81954940553. The reversal of 81954940531 is 13504945918.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81954940531 - 2¹⁵ = 81954907763 is a prime.

It is a super-2 number, since 2×81954940531² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81954944531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40977470265 + 40977470266.

It is an arithmetic number, because the mean of its divisors is an integer number (40977470266).

Almost surely, 2^81954940531 is an apocalyptic number.

81954940531 is a deficient number, since it is larger than the sum of its proper divisors (1).

81954940531 is an equidigital number, since it uses as much as digits as its factorization.

81954940531 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 777600, while the sum is 49.

The spelling of 81954940531 in words is "eighty-one billion, nine hundred fifty-four million, nine hundred forty thousand, five hundred thirty-one".