721011021121 has 4 divisors (see below), whose sum is σ = 721030633092. Its totient is φ = 720991409152.

The previous prime is 721011021091. The next prime is 721011021151. The reversal of 721011021121 is 121120110127.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (721011021091) and next prime (721011021151).

It can be written as a sum of positive squares in 2 ways, for example, as 2397081600 + 718613939521 = 48960^2 + 847711^2 .

It is a cyclic number.

It is not a de Polignac number, because 721011021121 - 2²¹ = 721008923969 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721011021151) 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, 9750736 + ... + 9824401.

It is an arithmetic number, because the mean of its divisors is an integer number (180257658273).

Almost surely, 2^721011021121 is an apocalyptic number.

It is an amenable number.

721011021121 is a deficient number, since it is larger than the sum of its proper divisors (19611971).

721011021121 is a wasteful number, since it uses less digits than its factorization.

721011021121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19611970.

The product of its (nonzero) digits is 56, while the sum is 19.

Adding to 721011021121 its reverse (121120110127), we get a palindrome (842131131248).

The spelling of 721011021121 in words is "seven hundred twenty-one billion, eleven million, twenty-one thousand, one hundred twenty-one".