21405673236 has 24 divisors (see below), whose sum is σ = 50765368864. Its totient is φ = 7018253280.

The previous prime is 21405673217. The next prime is 21405673243. The reversal of 21405673236 is 63237650412.

It is a junction number, because it is equal to n+sod(n) for n = 21405673194 and 21405673203.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14620630 + ... + 14622093.

Almost surely, 2^21405673236 is an apocalyptic number.

It is an amenable number.

21405673236 is an abundant number, since it is smaller than the sum of its proper divisors (29359695628).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21405673236 is a wasteful number, since it uses less digits than its factorization.

21405673236 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29242791 (or 29242789 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 39.

The spelling of 21405673236 in words is "twenty-one billion, four hundred five million, six hundred seventy-three thousand, two hundred thirty-six".