21653804738 has 8 divisors (see below), whose sum is σ = 33600731580. Its totient is φ = 10453560880.

The previous prime is 21653804707. The next prime is 21653804743. The reversal of 21653804738 is 83740835612.

It can be written as a sum of positive squares in 2 ways, for example, as 20311095289 + 1342709449 = 142517^2 + 36643^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 21653804692 and 21653804701.

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, 186670673 + ... + 186670788.

Almost surely, 2^21653804738 is an apocalyptic number.

21653804738 is a deficient number, since it is larger than the sum of its proper divisors (11946926842).

21653804738 is a wasteful number, since it uses less digits than its factorization.

21653804738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 373341492.

The product of its (nonzero) digits is 967680, while the sum is 47.

The spelling of 21653804738 in words is "twenty-one billion, six hundred fifty-three million, eight hundred four thousand, seven hundred thirty-eight".