21405105642 has 16 divisors (see below), whose sum is σ = 42843438720. Its totient is φ = 7129497312.

The previous prime is 21405105607. The next prime is 21405105661. The reversal of 21405105642 is 24650150412.

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, 1376098 + ... + 1391565.

It is an arithmetic number, because the mean of its divisors is an integer number (2677714920).

Almost surely, 2^21405105642 is an apocalyptic number.

21405105642 is an abundant number, since it is smaller than the sum of its proper divisors (21438333078).

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

21405105642 is a wasteful number, since it uses less digits than its factorization.

21405105642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2768957.

The product of its (nonzero) digits is 9600, while the sum is 30.

The spelling of 21405105642 in words is "twenty-one billion, four hundred five million, one hundred five thousand, six hundred forty-two".