81431563 has 2 divisors, whose sum is σ = 81431564. Its totient is φ = 81431562.

The previous prime is 81431527. The next prime is 81431579. The reversal of 81431563 is 36513418.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81431563 - 2¹³ = 81423371 is a prime.

It is not a weakly prime, because it can be changed into another prime (81431263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40715781 + 40715782.

It is an arithmetic number, because the mean of its divisors is an integer number (40715782).

Almost surely, 2^81431563 is an apocalyptic number.

81431563 is a deficient number, since it is larger than the sum of its proper divisors (1).

81431563 is an equidigital number, since it uses as much as digits as its factorization.

81431563 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8640, while the sum is 31.

The square root of 81431563 is about 9023.9438717226. The cubic root of 81431563 is about 433.4419320846.

The spelling of 81431563 in words is "eighty-one million, four hundred thirty-one thousand, five hundred sixty-three".