81499133 has 2 divisors, whose sum is σ = 81499134. Its totient is φ = 81499132.

The previous prime is 81499063. The next prime is 81499157. The reversal of 81499133 is 33199418.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 79530724 + 1968409 = 8918^2 + 1403^2 .

It is a cyclic number.

It is not a de Polignac number, because 81499133 - 2²⁶ = 14390269 is a prime.

It is equal to p_4751975 and since 81499133 and 4751975 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81499163) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40749566 + 40749567.

It is an arithmetic number, because the mean of its divisors is an integer number (40749567).

Almost surely, 2^81499133 is an apocalyptic number.

It is an amenable number.

81499133 is a deficient number, since it is larger than the sum of its proper divisors (1).

81499133 is an equidigital number, since it uses as much as digits as its factorization.

81499133 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23328, while the sum is 38.

The square root of 81499133 is about 9027.6870238173. The cubic root of 81499133 is about 433.5617855880.

The spelling of 81499133 in words is "eighty-one million, four hundred ninety-nine thousand, one hundred thirty-three".