81272745 has 12 divisors (see below), whose sum is σ = 140872836. Its totient is φ = 43345440.

The previous prime is 81272717. The next prime is 81272771. The reversal of 81272745 is 54727218.

It can be written as a sum of positive squares in 2 ways, for example, as 35426304 + 45846441 = 5952^2 + 6771^2 .

It is not a de Polignac number, because 81272745 - 2⁸ = 81272489 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 902986 + ... + 903075.

It is an arithmetic number, because the mean of its divisors is an integer number (11739403).

Almost surely, 2^81272745 is an apocalyptic number.

It is an amenable number.

81272745 is a deficient number, since it is larger than the sum of its proper divisors (59600091).

81272745 is a wasteful number, since it uses less digits than its factorization.

81272745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1806072 (or 1806069 counting only the distinct ones).

The product of its digits is 31360, while the sum is 36.

The square root of 81272745 is about 9015.1397659715. The cubic root of 81272745 is about 433.1599645068.

The spelling of 81272745 in words is "eighty-one million, two hundred seventy-two thousand, seven hundred forty-five".