21042306451 has 4 divisors (see below), whose sum is σ = 21045898872. Its totient is φ = 21038714032.

The previous prime is 21042306443. The next prime is 21042306463. The reversal of 21042306451 is 15460324012.

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 21042306451 - 2³ = 21042306443 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21042306431) 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, 1787410 + ... + 1799143.

It is an arithmetic number, because the mean of its divisors is an integer number (5261474718).

Almost surely, 2^21042306451 is an apocalyptic number.

21042306451 is a deficient number, since it is larger than the sum of its proper divisors (3592421).

21042306451 is an equidigital number, since it uses as much as digits as its factorization.

21042306451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3592420.

The product of its (nonzero) digits is 5760, while the sum is 28.

The spelling of 21042306451 in words is "twenty-one billion, forty-two million, three hundred six thousand, four hundred fifty-one".