721026121 has 4 divisors (see below), whose sum is σ = 722148112. Its totient is φ = 719904132.

The previous prime is 721026109. The next prime is 721026143. The reversal of 721026121 is 121620127.

It is a happy number.

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 721026121 - 2¹⁵ = 720993353 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 721026092 and 721026101.

It is not an unprimeable number, because it can be changed into a prime (721026721) 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, 560031 + ... + 561316.

It is an arithmetic number, because the mean of its divisors is an integer number (180537028).

Almost surely, 2^721026121 is an apocalyptic number.

It is an amenable number.

721026121 is a deficient number, since it is larger than the sum of its proper divisors (1121991).

721026121 is a wasteful number, since it uses less digits than its factorization.

721026121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1121990.

The product of its (nonzero) digits is 336, while the sum is 22.

The square root of 721026121 is about 26851.9295582273. The cubic root of 721026121 is about 896.7065308596.

Adding to 721026121 its reverse (121620127), we get a palindrome (842646248).

The spelling of 721026121 in words is "seven hundred twenty-one million, twenty-six thousand, one hundred twenty-one".