727979921 has 4 divisors (see below), whose sum is σ = 747655092. Its totient is φ = 708304752.

The previous prime is 727979911. The next prime is 727979929. The reversal of 727979921 is 129979727.

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 351037696 + 376942225 = 18736^2 + 19415^2 .

It is a cyclic number.

It is not a de Polignac number, because 727979921 - 2²² = 723785617 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (727979929) 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, 9837530 + ... + 9837603.

It is an arithmetic number, because the mean of its divisors is an integer number (186913773).

Almost surely, 2^727979921 is an apocalyptic number.

It is an amenable number.

727979921 is a deficient number, since it is larger than the sum of its proper divisors (19675171).

727979921 is a wasteful number, since it uses less digits than its factorization.

727979921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19675170.

The product of its digits is 1000188, while the sum is 53.

The square root of 727979921 is about 26981.1030352727. The cubic root of 727979921 is about 899.5800184510.

The spelling of 727979921 in words is "seven hundred twenty-seven million, nine hundred seventy-nine thousand, nine hundred twenty-one".