19521264449 has 4 divisors (see below), whose sum is σ = 20548699440. Its totient is φ = 18493829460.

The previous prime is 19521264401. The next prime is 19521264457. The reversal of 19521264449 is 94446212591.

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, and also an emirpimes, since its reverse is a distinct semiprime: 94446212591 = 223 ⋅423525617.

It is a cyclic number.

It is not a de Polignac number, because 19521264449 - 2³² = 15226297153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19521864449) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 513717467 + ... + 513717504.

It is an arithmetic number, because the mean of its divisors is an integer number (5137174860).

Almost surely, 2^19521264449 is an apocalyptic number.

19521264449 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

19521264449 is a deficient number, since it is larger than the sum of its proper divisors (1027434991).

19521264449 is a wasteful number, since it uses less digits than its factorization.

19521264449 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1027434990.

The product of its digits is 622080, while the sum is 47.

The spelling of 19521264449 in words is "nineteen billion, five hundred twenty-one million, two hundred sixty-four thousand, four hundred forty-nine".