21533643243 has 96 divisors (see below), whose sum is σ = 38321254400. Its totient is φ = 11628852480.

The previous prime is 21533643239. The next prime is 21533643247. The reversal of 21533643243 is 34234633512.

21533643243 is a `hidden beast` number, since 2 + 1 + 5 + 3 + 3 + 643 + 2 + 4 + 3 = 666.

It is an interprime number because it is at equal distance from previous prime (21533643239) and next prime (21533643247).

It is not a de Polignac number, because 21533643243 - 2² = 21533643239 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21533643198 and 21533643207.

It is not an unprimeable number, because it can be changed into a prime (21533643247) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 4112355 + ... + 4117587.

Almost surely, 2^21533643243 is an apocalyptic number.

21533643243 is a deficient number, since it is larger than the sum of its proper divisors (16787611157).

21533643243 is a wasteful number, since it uses less digits than its factorization.

21533643243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5334 (or 5317 counting only the distinct ones).

The product of its digits is 155520, while the sum is 36.

The spelling of 21533643243 in words is "twenty-one billion, five hundred thirty-three million, six hundred forty-three thousand, two hundred forty-three".