82611721 has 4 divisors (see below), whose sum is σ = 87471252. Its totient is φ = 77752192.

The previous prime is 82611707. The next prime is 82611733. The reversal of 82611721 is 12711628.

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 58982400 + 23629321 = 7680^2 + 4861^2 .

It is a cyclic number.

It is not a de Polignac number, because 82611721 - 2⁵ = 82611689 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 82611721.

It is not an unprimeable number, because it can be changed into a prime (82611421) 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, 2429740 + ... + 2429773.

It is an arithmetic number, because the mean of its divisors is an integer number (21867813).

Almost surely, 2^82611721 is an apocalyptic number.

It is an amenable number.

82611721 is a deficient number, since it is larger than the sum of its proper divisors (4859531).

82611721 is a wasteful number, since it uses less digits than its factorization.

82611721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4859530.

The product of its digits is 1344, while the sum is 28.

The square root of 82611721 is about 9089.0990202550. The cubic root of 82611721 is about 435.5258027273.

The spelling of 82611721 in words is "eighty-two million, six hundred eleven thousand, seven hundred twenty-one".