81670765 has 24 divisors (see below), whose sum is σ = 109539864. Its totient is φ = 58396800.

The previous prime is 81670763. The next prime is 81670781. The reversal of 81670765 is 56707618.

It can be written as a sum of positive squares in 4 ways, for example, as 10673289 + 70997476 = 3267^2 + 8426^2 .

It is not a de Polignac number, because 81670765 - 2¹ = 81670763 is a prime.

It is a super-2 number, since 2×81670765² = 13340227711370450, which contains 22 as substring.

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

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81670763) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 35799 + ... + 38011.

It is an arithmetic number, because the mean of its divisors is an integer number (4564161).

Almost surely, 2^81670765 is an apocalyptic number.

It is an amenable number.

81670765 is a deficient number, since it is larger than the sum of its proper divisors (27869099).

81670765 is a wasteful number, since it uses less digits than its factorization.

81670765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2301 (or 2290 counting only the distinct ones).

The product of its (nonzero) digits is 70560, while the sum is 40.

The square root of 81670765 is about 9037.1878922594. The cubic root of 81670765 is about 433.8659233879.

The spelling of 81670765 in words is "eighty-one million, six hundred seventy thousand, seven hundred sixty-five".