21645412741 has 4 divisors (see below), whose sum is σ = 22918672332. Its totient is φ = 20372153152.

The previous prime is 21645412727. The next prime is 21645412771. The reversal of 21645412741 is 14721454612.

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 20200652641 + 1444760100 = 142129^2 + 38010^2 .

It is a cyclic number.

It is not a de Polignac number, because 21645412741 - 2¹⁹ = 21644888453 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21645412741.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21645412771) 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, 636629770 + ... + 636629803.

It is an arithmetic number, because the mean of its divisors is an integer number (5729668083).

Almost surely, 2^21645412741 is an apocalyptic number.

It is an amenable number.

21645412741 is a deficient number, since it is larger than the sum of its proper divisors (1273259591).

21645412741 is a wasteful number, since it uses less digits than its factorization.

21645412741 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1273259590.

The product of its digits is 53760, while the sum is 37.

The spelling of 21645412741 in words is "twenty-one billion, six hundred forty-five million, four hundred twelve thousand, seven hundred forty-one".