81402613 has 4 divisors (see below), whose sum is σ = 86191020. Its totient is φ = 76614208.

The previous prime is 81402571. The next prime is 81402641. The reversal of 81402613 is 31620418.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 53333809 + 28068804 = 7303^2 + 5298^2 .

It is a cyclic number.

It is not a de Polignac number, because 81402613 - 2¹³ = 81394421 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81402653) 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, 2394178 + ... + 2394211.

It is an arithmetic number, because the mean of its divisors is an integer number (21547755).

Almost surely, 2^81402613 is an apocalyptic number.

It is an amenable number.

81402613 is a deficient number, since it is larger than the sum of its proper divisors (4788407).

81402613 is a wasteful number, since it uses less digits than its factorization.

81402613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4788406.

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 81402613 is about 9022.3396633024. The cubic root of 81402613 is about 433.3905612125.

The spelling of 81402613 in words is "eighty-one million, four hundred two thousand, six hundred thirteen".