21630444521 has 4 divisors (see below), whose sum is σ = 24720508032. Its totient is φ = 18540381012.

The previous prime is 21630444487. The next prime is 21630444601. The reversal of 21630444521 is 12544403612.

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 21630444521 - 2⁶ = 21630444457 is a prime.

It is a super-2 number, since 2×21630444521² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21630440521) 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, 1545031745 + ... + 1545031758.

It is an arithmetic number, because the mean of its divisors is an integer number (6180127008).

Almost surely, 2^21630444521 is an apocalyptic number.

It is an amenable number.

21630444521 is a deficient number, since it is larger than the sum of its proper divisors (3090063511).

21630444521 is an equidigital number, since it uses as much as digits as its factorization.

21630444521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3090063510.

The product of its (nonzero) digits is 23040, while the sum is 32.

The spelling of 21630444521 in words is "twenty-one billion, six hundred thirty million, four hundred forty-four thousand, five hundred twenty-one".