83120721 has 4 divisors (see below), whose sum is σ = 110827632. Its totient is φ = 55413812.

The previous prime is 83120711. The next prime is 83120747. The reversal of 83120721 is 12702138.

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 83120721 - 2⁶ = 83120657 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 83120691 and 83120700.

It is not an unprimeable number, because it can be changed into a prime (83120711) 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, 13853451 + ... + 13853456.

It is an arithmetic number, because the mean of its divisors is an integer number (27706908).

Almost surely, 2^83120721 is an apocalyptic number.

It is an amenable number.

83120721 is a deficient number, since it is larger than the sum of its proper divisors (27706911).

83120721 is a wasteful number, since it uses less digits than its factorization.

83120721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27706910.

The product of its (nonzero) digits is 672, while the sum is 24.

The square root of 83120721 is about 9117.0565973893. The cubic root of 83120721 is about 436.4184480430.

Adding to 83120721 its reverse (12702138), we get a palindrome (95822859).

The spelling of 83120721 in words is "eighty-three million, one hundred twenty thousand, seven hundred twenty-one".