10221805721 has 4 divisors (see below), whose sum is σ = 10222185744. Its totient is φ = 10221425700.

The previous prime is 10221805663. The next prime is 10221805757. The reversal of 10221805721 is 12750812201.

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 a de Polignac number, because none of the positive numbers 2^k-10221805721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (10221805771) 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, 146315 + ... + 204576.

It is an arithmetic number, because the mean of its divisors is an integer number (2555546436).

Almost surely, 2^10221805721 is an apocalyptic number.

It is an amenable number.

10221805721 is a deficient number, since it is larger than the sum of its proper divisors (380023).

10221805721 is an equidigital number, since it uses as much as digits as its factorization.

10221805721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 380022.

The product of its (nonzero) digits is 2240, while the sum is 29.

The spelling of 10221805721 in words is "ten billion, two hundred twenty-one million, eight hundred five thousand, seven hundred twenty-one".