81907445 has 16 divisors (see below), whose sum is σ = 105783408. Its totient is φ = 60656640.

The previous prime is 81907421. The next prime is 81907447. The reversal of 81907445 is 54470918.

It can be written as a sum of positive squares in 8 ways, for example, as 925444 + 80982001 = 962^2 + 8999^2 .

It is a de Polignac number, because none of the positive numbers 2^k-81907445 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81907399 and 81907408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81907447) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2714 + ... + 13083.

It is an arithmetic number, because the mean of its divisors is an integer number (6611463).

Almost surely, 2^81907445 is an apocalyptic number.

81907445 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

It is an amenable number.

81907445 is a deficient number, since it is larger than the sum of its proper divisors (23875963).

81907445 is a wasteful number, since it uses less digits than its factorization.

81907445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15880.

The product of its (nonzero) digits is 40320, while the sum is 38.

The square root of 81907445 is about 9050.2732002962. The cubic root of 81907445 is about 434.2846303386.

The spelling of 81907445 in words is "eighty-one million, nine hundred seven thousand, four hundred forty-five".