81670013 has 8 divisors (see below), whose sum is σ = 82401528. Its totient is φ = 80941824.

The previous prime is 81670007. The next prime is 81670019. The reversal of 81670013 is 31007618.

It is an interprime number because it is at equal distance from previous prime (81670007) and next prime (81670019).

It can be written as a sum of positive squares in 4 ways, for example, as 67207204 + 14462809 = 8198^2 + 3803^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81670013 - 2¹⁴ = 81653629 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81670019) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 78545 + ... + 79577.

It is an arithmetic number, because the mean of its divisors is an integer number (10300191).

Almost surely, 2^81670013 is an apocalyptic number.

It is an amenable number.

81670013 is a deficient number, since it is larger than the sum of its proper divisors (731515).

81670013 is a wasteful number, since it uses less digits than its factorization.

81670013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1663.

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 81670013 is about 9037.1462863008. The cubic root of 81670013 is about 433.8645917479.

The spelling of 81670013 in words is "eighty-one million, six hundred seventy thousand, thirteen".