21683917953 has 6 divisors (see below), whose sum is σ = 31321214834. Its totient is φ = 14455945296.

The previous prime is 21683917951. The next prime is 21683917963. The reversal of 21683917953 is 35971938612.

21683917953 is a `hidden beast` number, since 2 + 168 + 391 + 7 + 95 + 3 = 666.

It can be written as a sum of positive squares in only one way, i.e., 13843169649 + 7840748304 = 117657^2 + 88548^2 .

It is not a de Polignac number, because 21683917953 - 2¹ = 21683917951 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21683917953.

It is not an unprimeable number, because it can be changed into a prime (21683917951) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1204662100 + ... + 1204662117.

Almost surely, 2^21683917953 is an apocalyptic number.

It is an amenable number.

21683917953 is a deficient number, since it is larger than the sum of its proper divisors (9637296881).

21683917953 is a wasteful number, since it uses less digits than its factorization.

21683917953 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2409324223 (or 2409324220 counting only the distinct ones).

The product of its digits is 2449440, while the sum is 54.

The spelling of 21683917953 in words is "twenty-one billion, six hundred eighty-three million, nine hundred seventeen thousand, nine hundred fifty-three".