81625405 has 8 divisors (see below), whose sum is σ = 98286552. Its totient is φ = 65076288.

The previous prime is 81625393. The next prime is 81625409. The reversal of 81625405 is 50452618.

It can be written as a sum of positive squares in 4 ways, for example, as 46744569 + 34880836 = 6837^2 + 5906^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81625405 - 2²³ = 73236797 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81625409) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26394 + ... + 29323.

It is an arithmetic number, because the mean of its divisors is an integer number (12285819).

Almost surely, 2^81625405 is an apocalyptic number.

It is an amenable number.

81625405 is a deficient number, since it is larger than the sum of its proper divisors (16661147).

81625405 is a wasteful number, since it uses less digits than its factorization.

81625405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56015.

The product of its (nonzero) digits is 9600, while the sum is 31.

The square root of 81625405 is about 9034.6779134621. The cubic root of 81625405 is about 433.7855853670.

The spelling of 81625405 in words is "eighty-one million, six hundred twenty-five thousand, four hundred five".