81490393 has 2 divisors, whose sum is σ = 81490394. Its totient is φ = 81490392.

The previous prime is 81490369. The next prime is 81490399. The reversal of 81490393 is 39309418.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76790169 + 4700224 = 8763^2 + 2168^2 .

It is a cyclic number.

It is not a de Polignac number, because 81490393 - 2¹³ = 81482201 is a prime.

It is not a weakly prime, because it can be changed into another prime (81490399) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40745196 + 40745197.

It is an arithmetic number, because the mean of its divisors is an integer number (40745197).

Almost surely, 2^81490393 is an apocalyptic number.

It is an amenable number.

81490393 is a deficient number, since it is larger than the sum of its proper divisors (1).

81490393 is an equidigital number, since it uses as much as digits as its factorization.

81490393 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23328, while the sum is 37.

The square root of 81490393 is about 9027.2029444341. The cubic root of 81490393 is about 433.5462865869.

It can be divided in two parts, 8 and 1490393, that added together give a triangular number (1490401 = T₁₇₂₆).

The spelling of 81490393 in words is "eighty-one million, four hundred ninety thousand, three hundred ninety-three".