9721009621 has 2 divisors, whose sum is σ = 9721009622. Its totient is φ = 9721009620.

The previous prime is 9721009601. The next prime is 9721009633. The reversal of 9721009621 is 1269001279.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6591166596 + 3129843025 = 81186^2 + 55945^2 .

It is a cyclic number.

It is not a de Polignac number, because 9721009621 - 2⁵ = 9721009589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9721009601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4860504810 + 4860504811.

It is an arithmetic number, because the mean of its divisors is an integer number (4860504811).

Almost surely, 2^9721009621 is an apocalyptic number.

It is an amenable number.

9721009621 is a deficient number, since it is larger than the sum of its proper divisors (1).

9721009621 is an equidigital number, since it uses as much as digits as its factorization.

9721009621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13608, while the sum is 37.

The square root of 9721009621 is about 98595.1805160881. The cubic root of 9721009621 is about 2134.2098713740.

The spelling of 9721009621 in words is "nine billion, seven hundred twenty-one million, nine thousand, six hundred twenty-one".