21429640445 has 18 divisors (see below), whose sum is σ = 27324325626. Its totient is φ = 16131068800.

The previous prime is 21429640439. The next prime is 21429640457. The reversal of 21429640445 is 54404692412.

It can be written as a sum of positive squares in 3 ways, for example, as 7177817284 + 14251823161 = 84722^2 + 119381^2 .

It is not a de Polignac number, because 21429640445 - 2⁴ = 21429640429 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 17 ways as a sum of consecutive naturals, for example, 5562770 + ... + 5566620.

Almost surely, 2^21429640445 is an apocalyptic number.

It is an amenable number.

21429640445 is a deficient number, since it is larger than the sum of its proper divisors (5894685181).

21429640445 is an frugal number, since it uses more digits than its factorization.

21429640445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7741 (or 3873 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 41.

The spelling of 21429640445 in words is "twenty-one billion, four hundred twenty-nine million, six hundred forty thousand, four hundred forty-five".