21449491021 has 4 divisors (see below), whose sum is σ = 24513704032. Its totient is φ = 18385278012.

The previous prime is 21449490991. The next prime is 21449491027. The reversal of 21449491021 is 12019494412.

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 21449491021 - 2¹⁵ = 21449458253 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21449491027) 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, 1532106495 + ... + 1532106508.

It is an arithmetic number, because the mean of its divisors is an integer number (6128426008).

Almost surely, 2^21449491021 is an apocalyptic number.

It is an amenable number.

21449491021 is a deficient number, since it is larger than the sum of its proper divisors (3064213011).

21449491021 is an equidigital number, since it uses as much as digits as its factorization.

21449491021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3064213010.

The product of its (nonzero) digits is 20736, while the sum is 37.

The spelling of 21449491021 in words is "twenty-one billion, four hundred forty-nine million, four hundred ninety-one thousand, twenty-one".