21008895451 has 4 divisors (see below), whose sum is σ = 21922325712. Its totient is φ = 20095465192.

The previous prime is 21008895431. The next prime is 21008895469. The reversal of 21008895451 is 15459880012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21008895451 - 2²⁵ = 20975341019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21008895398 and 21008895407.

It is not an unprimeable number, because it can be changed into a prime (21008895431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 456715096 + ... + 456715141.

It is an arithmetic number, because the mean of its divisors is an integer number (5480581428).

Almost surely, 2^21008895451 is an apocalyptic number.

21008895451 is a deficient number, since it is larger than the sum of its proper divisors (913430261).

21008895451 is an equidigital number, since it uses as much as digits as its factorization.

21008895451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 913430260.

The product of its (nonzero) digits is 115200, while the sum is 43.

The spelling of 21008895451 in words is "twenty-one billion, eight million, eight hundred ninety-five thousand, four hundred fifty-one".