81313373 has 4 divisors (see below), whose sum is σ = 83296668. Its totient is φ = 79330080.

The previous prime is 81313367. The next prime is 81313381. The reversal of 81313373 is 37331318.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 37331318 = 2 ⋅18665659.

It can be written as a sum of positive squares in 2 ways, for example, as 14122564 + 67190809 = 3758^2 + 8197^2 .

It is not a de Polignac number, because 81313373 - 2⁸ = 81313117 is a prime.

It is a super-2 number, since 2×81313373² = 13223729257274258, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81313333) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 991586 + ... + 991667.

It is an arithmetic number, because the mean of its divisors is an integer number (20824167).

Almost surely, 2^81313373 is an apocalyptic number.

It is an amenable number.

81313373 is a deficient number, since it is larger than the sum of its proper divisors (1983295).

81313373 is a wasteful number, since it uses less digits than its factorization.

81313373 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1983294.

The product of its digits is 4536, while the sum is 29.

The square root of 81313373 is about 9017.3928050185. The cubic root of 81313373 is about 433.2321309360.

The spelling of 81313373 in words is "eighty-one million, three hundred thirteen thousand, three hundred seventy-three".