9921621901 has 4 divisors (see below), whose sum is σ = 9927955072. Its totient is φ = 9915288732.

The previous prime is 9921621887. The next prime is 9921621937. The reversal of 9921621901 is 1091261299.

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 9921621901 - 2⁵ = 9921621869 is a prime.

It is a super-2 number, since 2×9921621901² (a number of 21 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 (9921621961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3164235 + ... + 3167368.

It is an arithmetic number, because the mean of its divisors is an integer number (2481988768).

Almost surely, 2^9921621901 is an apocalyptic number.

It is an amenable number.

9921621901 is a deficient number, since it is larger than the sum of its proper divisors (6333171).

9921621901 is a wasteful number, since it uses less digits than its factorization.

9921621901 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6333170.

The product of its (nonzero) digits is 17496, while the sum is 40.

The square root of 9921621901 is about 99607.3385900858. The cubic root of 9921621901 is about 2148.7912369655.

The spelling of 9921621901 in words is "nine billion, nine hundred twenty-one million, six hundred twenty-one thousand, nine hundred one".