81390499 has 2 divisors, whose sum is σ = 81390500. Its totient is φ = 81390498.

The previous prime is 81390487. The next prime is 81390503. The reversal of 81390499 is 99409318.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81390499 - 2¹³ = 81382307 is a prime.

It is not a weakly prime, because it can be changed into another prime (81390479) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40695249 + 40695250.

It is an arithmetic number, because the mean of its divisors is an integer number (40695250).

Almost surely, 2^81390499 is an apocalyptic number.

81390499 is a deficient number, since it is larger than the sum of its proper divisors (1).

81390499 is an equidigital number, since it uses as much as digits as its factorization.

81390499 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 69984, while the sum is 43.

The square root of 81390499 is about 9021.6683046984. The cubic root of 81390499 is about 433.3690616826.

The spelling of 81390499 in words is "eighty-one million, three hundred ninety thousand, four hundred ninety-nine".