721002121021 has 16 divisors (see below), whose sum is σ = 899885645568. Its totient is φ = 562428518400.

The previous prime is 721002121013. The next prime is 721002121057. The reversal of 721002121021 is 120121200127.

It is not a de Polignac number, because 721002121021 - 2³ = 721002121013 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 721002121021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721002121001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 55790020 + ... + 55802941.

It is an arithmetic number, because the mean of its divisors is an integer number (56242852848).

Almost surely, 2^721002121021 is an apocalyptic number.

721002121021 is a gapful number since it is divisible by the number (71) formed by its first and last digit.

It is an amenable number.

721002121021 is a deficient number, since it is larger than the sum of its proper divisors (178883524547).

721002121021 is a wasteful number, since it uses less digits than its factorization.

721002121021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111593052.

The product of its (nonzero) digits is 112, while the sum is 19.

Adding to 721002121021 its reverse (120121200127), we get a palindrome (841123321148).

The spelling of 721002121021 in words is "seven hundred twenty-one billion, two million, one hundred twenty-one thousand, twenty-one".