21451332447 has 12 divisors (see below), whose sum is σ = 31447725400. Its totient is φ = 14087441808.

The previous prime is 21451332439. The next prime is 21451332449. The reversal of 21451332447 is 74423315412.

It is not a de Polignac number, because 21451332447 - 2³ = 21451332439 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 (21451332449) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17786572 + ... + 17787777.

Almost surely, 2^21451332447 is an apocalyptic number.

21451332447 is a deficient number, since it is larger than the sum of its proper divisors (9996392953).

21451332447 is a wasteful number, since it uses less digits than its factorization.

21451332447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35574422 (or 35574419 counting only the distinct ones).

The product of its digits is 80640, while the sum is 36.

Adding to 21451332447 its reverse (74423315412), we get a palindrome (95874647859).

The spelling of 21451332447 in words is "twenty-one billion, four hundred fifty-one million, three hundred thirty-two thousand, four hundred forty-seven".