21517482451 has 4 divisors (see below), whose sum is σ = 21517778304. Its totient is φ = 21517186600.

The previous prime is 21517482439. The next prime is 21517482457. The reversal of 21517482451 is 15428471512.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21517482451 - 2⁵ = 21517482419 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21517482457) 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, 45321 + ... + 212341.

It is an arithmetic number, because the mean of its divisors is an integer number (5379444576).

Almost surely, 2^21517482451 is an apocalyptic number.

21517482451 is a deficient number, since it is larger than the sum of its proper divisors (295853).

21517482451 is a wasteful number, since it uses less digits than its factorization.

21517482451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 295852.

The product of its digits is 89600, while the sum is 40.

The spelling of 21517482451 in words is "twenty-one billion, five hundred seventeen million, four hundred eighty-two thousand, four hundred fifty-one".