21861311638 has 8 divisors (see below), whose sum is σ = 33329540880. Its totient is φ = 10751464680.

The previous prime is 21861311629. The next prime is 21861311683. The reversal of 21861311638 is 83611316812.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21861311638.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 89595418 + ... + 89595661.

It is an arithmetic number, because the mean of its divisors is an integer number (4166192610).

Almost surely, 2^21861311638 is an apocalyptic number.

21861311638 is a deficient number, since it is larger than the sum of its proper divisors (11468229242).

21861311638 is a wasteful number, since it uses less digits than its factorization.

21861311638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 179191142.

The product of its digits is 41472, while the sum is 40.

The spelling of 21861311638 in words is "twenty-one billion, eight hundred sixty-one million, three hundred eleven thousand, six hundred thirty-eight".