81408637 has 4 divisors (see below), whose sum is σ = 81434016. Its totient is φ = 81383260.

The previous prime is 81408623. The next prime is 81408643. The reversal of 81408637 is 73680418.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81408637 - 2²³ = 73020029 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81408596 and 81408605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81408617) 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, 7039 + ... + 14572.

It is an arithmetic number, because the mean of its divisors is an integer number (20358504).

Almost surely, 2^81408637 is an apocalyptic number.

It is an amenable number.

81408637 is a deficient number, since it is larger than the sum of its proper divisors (25379).

81408637 is a wasteful number, since it uses less digits than its factorization.

81408637 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25378.

The product of its (nonzero) digits is 32256, while the sum is 37.

The square root of 81408637 is about 9022.6734951454. The cubic root of 81408637 is about 433.4012516160.

The spelling of 81408637 in words is "eighty-one million, four hundred eight thousand, six hundred thirty-seven".