81670740 has 96 divisors (see below), whose sum is σ = 248586240. Its totient is φ = 19958400.

The previous prime is 81670733. The next prime is 81670747. The reversal of 81670740 is 4707618.

It is an interprime number because it is at equal distance from previous prime (81670733) and next prime (81670747).

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81670747) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 34185 + ... + 36495.

It is an arithmetic number, because the mean of its divisors is an integer number (2589440).

Almost surely, 2^81670740 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81670740, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (124293120).

81670740 is an abundant number, since it is smaller than the sum of its proper divisors (166915500).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81670740 is a wasteful number, since it uses less digits than its factorization.

81670740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2373 (or 2371 counting only the distinct ones).

The product of its (nonzero) digits is 9408, while the sum is 33.

The square root of 81670740 is about 9037.1865090857. The cubic root of 81670740 is about 433.8658791181.

The spelling of 81670740 in words is "eighty-one million, six hundred seventy thousand, seven hundred forty".