21519305918 has 16 divisors (see below), whose sum is σ = 35637670656. Its totient is φ = 9663652440.

The previous prime is 21519305911. The next prime is 21519305923. The reversal of 21519305918 is 81950391512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21519305911) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5890646 + ... + 5894297.

It is an arithmetic number, because the mean of its divisors is an integer number (2227354416).

Almost surely, 2^21519305918 is an apocalyptic number.

21519305918 is a deficient number, since it is larger than the sum of its proper divisors (14118364738).

21519305918 is a wasteful number, since it uses less digits than its factorization.

21519305918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11785039.

The product of its (nonzero) digits is 97200, while the sum is 44.

The spelling of 21519305918 in words is "twenty-one billion, five hundred nineteen million, three hundred five thousand, nine hundred eighteen".