7991221001021 has 4 divisors (see below), whose sum is σ = 7991226982944. Its totient is φ = 7991215019100.

The previous prime is 7991221001011. The next prime is 7991221001033. The reversal of 7991221001021 is 1201001221997.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 7991221001021 - 2²⁶ = 7991153892157 is a prime.

It is a super-2 number, since 2×7991221001021² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7991221001011) 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, 29906 + ... + 3997916.

It is an arithmetic number, because the mean of its divisors is an integer number (1997806745736).

Almost surely, 2^{7991221001021} is an apocalyptic number.

It is an amenable number.

7991221001021 is a deficient number, since it is larger than the sum of its proper divisors (5981923).

7991221001021 is a wasteful number, since it uses less digits than its factorization.

7991221001021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5981922.

The product of its (nonzero) digits is 4536, while the sum is 35.

The spelling of 7991221001021 in words is "seven trillion, nine hundred ninety-one billion, two hundred twenty-one million, one thousand, twenty-one".