83615721 has 16 divisors (see below), whose sum is σ = 127918464. Its totient is φ = 47591424.

The previous prime is 83615717. The next prime is 83615737. The reversal of 83615721 is 12751638.

It is not a de Polignac number, because 83615721 - 2² = 83615717 is a prime.

It is not an unprimeable number, because it can be changed into a prime (83615761) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2350 + ... + 13143.

It is an arithmetic number, because the mean of its divisors is an integer number (7994904).

Almost surely, 2^83615721 is an apocalyptic number.

It is an amenable number.

83615721 is a deficient number, since it is larger than the sum of its proper divisors (44302743).

83615721 is a wasteful number, since it uses less digits than its factorization.

83615721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15760.

The product of its digits is 10080, while the sum is 33.

The square root of 83615721 is about 9144.1632203280. The cubic root of 83615721 is about 437.2830528191.

The spelling of 83615721 in words is "eighty-three million, six hundred fifteen thousand, seven hundred twenty-one".