81431527 has 2 divisors, whose sum is σ = 81431528. Its totient is φ = 81431526.

The previous prime is 81431509. The next prime is 81431563. The reversal of 81431527 is 72513418.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81431527 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81431027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40715763 + 40715764.

It is an arithmetic number, because the mean of its divisors is an integer number (40715764).

Almost surely, 2^81431527 is an apocalyptic number.

81431527 is a deficient number, since it is larger than the sum of its proper divisors (1).

81431527 is an equidigital number, since it uses as much as digits as its factorization.

81431527 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6720, while the sum is 31.

The square root of 81431527 is about 9023.9418770291. The cubic root of 81431527 is about 433.4418682113.

The spelling of 81431527 in words is "eighty-one million, four hundred thirty-one thousand, five hundred twenty-seven".