21653442788 has 6 divisors (see below), whose sum is σ = 37893524886. Its totient is φ = 10826721392.

The previous prime is 21653442761. The next prime is 21653442821. The reversal of 21653442788 is 88724435612.

It can be written as a sum of positive squares in only one way, i.e., 16463969344 + 5189473444 = 128312^2 + 72038^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2706680345 + ... + 2706680352.

It is an arithmetic number, because the mean of its divisors is an integer number (6315587481).

Almost surely, 2^21653442788 is an apocalyptic number.

It is an amenable number.

21653442788 is a deficient number, since it is larger than the sum of its proper divisors (16240082098).

21653442788 is a wasteful number, since it uses less digits than its factorization.

21653442788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5413360701 (or 5413360699 counting only the distinct ones).

The product of its digits is 2580480, while the sum is 50.

The spelling of 21653442788 in words is "twenty-one billion, six hundred fifty-three million, four hundred forty-two thousand, seven hundred eighty-eight".