21964578541 has 4 divisors (see below), whose sum is σ = 21964929084. Its totient is φ = 21964228000.

The previous prime is 21964578539. The next prime is 21964578557. The reversal of 21964578541 is 14587546912.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1185356041 + 20779222500 = 34429^2 + 144150^2 .

It is a cyclic number.

It is not a de Polignac number, because 21964578541 - 2¹ = 21964578539 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 (21964575541) 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, 52720 + ... + 216121.

It is an arithmetic number, because the mean of its divisors is an integer number (5491232271).

Almost surely, 2^21964578541 is an apocalyptic number.

It is an amenable number.

21964578541 is a deficient number, since it is larger than the sum of its proper divisors (350543).

21964578541 is an equidigital number, since it uses as much as digits as its factorization.

21964578541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 350542.

The product of its digits is 2419200, while the sum is 52.

The spelling of 21964578541 in words is "twenty-one billion, nine hundred sixty-four million, five hundred seventy-eight thousand, five hundred forty-one".