81556545 has 16 divisors (see below), whose sum is σ = 149132160. Its totient is φ = 37282944.

The previous prime is 81556537. The next prime is 81556571. The reversal of 81556545 is 54565518.

It is not a de Polignac number, because 81556545 - 2³ = 81556537 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 388260 + ... + 388469.

It is an arithmetic number, because the mean of its divisors is an integer number (9320760).

Almost surely, 2^81556545 is an apocalyptic number.

It is an amenable number.

81556545 is a deficient number, since it is larger than the sum of its proper divisors (67575615).

81556545 is a wasteful number, since it uses less digits than its factorization.

81556545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 776744.

The product of its digits is 120000, while the sum is 39.

The square root of 81556545 is about 9030.8662375212. The cubic root of 81556545 is about 433.6635691107.

The spelling of 81556545 in words is "eighty-one million, five hundred fifty-six thousand, five hundred forty-five".