21540603645 has 64 divisors (see below), whose sum is σ = 41805953280. Its totient is φ = 10436371200.

The previous prime is 21540603641. The next prime is 21540603647. The reversal of 21540603645 is 54630604512.

21540603645 is a `hidden beast` number, since 2 + 1 + 5 + 4 + 0 + 6 + 0 + 3 + 645 = 666.

It is not a de Polignac number, because 21540603645 - 2² = 21540603641 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21540603641) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2426515 + ... + 2435375.

It is an arithmetic number, because the mean of its divisors is an integer number (653218020).

Almost surely, 2^21540603645 is an apocalyptic number.

It is an amenable number.

21540603645 is a deficient number, since it is larger than the sum of its proper divisors (20265349635).

21540603645 is a wasteful number, since it uses less digits than its factorization.

21540603645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10523 (or 10517 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 36.

The spelling of 21540603645 in words is "twenty-one billion, five hundred forty million, six hundred three thousand, six hundred forty-five".