721796121 has 6 divisors (see below), whose sum is σ = 1042594410. Its totient is φ = 481197408.

The previous prime is 721796093. The next prime is 721796129. The reversal of 721796121 is 121697127.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 652240521 + 69555600 = 25539^2 + 8340^2 .

It is not a de Polignac number, because 721796121 - 2⁶ = 721796057 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (721796129) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 40099776 + ... + 40099793.

It is an arithmetic number, because the mean of its divisors is an integer number (173765735).

Almost surely, 2^721796121 is an apocalyptic number.

It is an amenable number.

721796121 is a deficient number, since it is larger than the sum of its proper divisors (320798289).

721796121 is a wasteful number, since it uses less digits than its factorization.

721796121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80199575 (or 80199572 counting only the distinct ones).

The product of its digits is 10584, while the sum is 36.

The square root of 721796121 is about 26866.2636218734. The cubic root of 721796121 is about 897.0256216512.

The spelling of 721796121 in words is "seven hundred twenty-one million, seven hundred ninety-six thousand, one hundred twenty-one".