20997409449 has 4 divisors (see below), whose sum is σ = 27996545936. Its totient is φ = 13998272964.

The previous prime is 20997409403. The next prime is 20997409493. The reversal of 20997409449 is 94490479902.

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 not a de Polignac number, because 20997409449 - 2¹² = 20997405353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20997409549) 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, 3499568239 + ... + 3499568244.

It is an arithmetic number, because the mean of its divisors is an integer number (6999136484).

Almost surely, 2^20997409449 is an apocalyptic number.

It is an amenable number.

20997409449 is a deficient number, since it is larger than the sum of its proper divisors (6999136487).

20997409449 is an equidigital number, since it uses as much as digits as its factorization.

20997409449 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6999136486.

The product of its (nonzero) digits is 5878656, while the sum is 57.

The spelling of 20997409449 in words is "twenty billion, nine hundred ninety-seven million, four hundred nine thousand, four hundred forty-nine".