81504913 has 4 divisors (see below), whose sum is σ = 93148480. Its totient is φ = 69861348.

The previous prime is 81504911. The next prime is 81504923. The reversal of 81504913 is 31940518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81504913 - 2¹ = 81504911 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81504911) 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, 5821773 + ... + 5821786.

It is an arithmetic number, because the mean of its divisors is an integer number (23287120).

Almost surely, 2^81504913 is an apocalyptic number.

It is an amenable number.

81504913 is a deficient number, since it is larger than the sum of its proper divisors (11643567).

81504913 is a wasteful number, since it uses less digits than its factorization.

81504913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11643566.

The product of its (nonzero) digits is 4320, while the sum is 31.

The square root of 81504913 is about 9028.0071444367. The cubic root of 81504913 is about 433.5720348908.

The spelling of 81504913 in words is "eighty-one million, five hundred four thousand, nine hundred thirteen".