21561000548 has 12 divisors (see below), whose sum is σ = 37733174892. Its totient is φ = 10780093440.

The previous prime is 21561000529. The next prime is 21561000569. The reversal of 21561000548 is 84500016512.

It can be written as a sum of positive squares in 2 ways, for example, as 8958243904 + 12602756644 = 94648^2 + 112262^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 39236 + ... + 211332.

It is an arithmetic number, because the mean of its divisors is an integer number (3144431241).

Almost surely, 2^21561000548 is an apocalyptic number.

It is an amenable number.

21561000548 is a deficient number, since it is larger than the sum of its proper divisors (16172174344).

21561000548 is a wasteful number, since it uses less digits than its factorization.

21561000548 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 203422 (or 203420 counting only the distinct ones).

The product of its (nonzero) digits is 9600, while the sum is 32.

The spelling of 21561000548 in words is "twenty-one billion, five hundred sixty-one million, five hundred forty-eight", and thus it is an aban number.