81404599 has 4 divisors (see below), whose sum is σ = 81638200. Its totient is φ = 81171000.

The previous prime is 81404593. The next prime is 81404621. The reversal of 81404599 is 99540418.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99540418 = 2 ⋅49770209.

It is a cyclic number.

It is not a de Polignac number, because 81404599 - 2³ = 81404591 is a prime.

It is a super-3 number, since 3×81404599³ (a number of 25 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81404591) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 116277 + ... + 116974.

It is an arithmetic number, because the mean of its divisors is an integer number (20409550).

Almost surely, 2^81404599 is an apocalyptic number.

81404599 is a deficient number, since it is larger than the sum of its proper divisors (233601).

81404599 is a wasteful number, since it uses less digits than its factorization.

81404599 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 233600.

The product of its (nonzero) digits is 51840, while the sum is 40.

The square root of 81404599 is about 9022.4497227749. The cubic root of 81404599 is about 433.3940856966.

The spelling of 81404599 in words is "eighty-one million, four hundred four thousand, five hundred ninety-nine".