21138267686 has 4 divisors (see below), whose sum is σ = 31707401532. Its totient is φ = 10569133842.

The previous prime is 21138267677. The next prime is 21138267701. The reversal of 21138267686 is 68676283112.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5284566920 + ... + 5284566923.

It is an arithmetic number, because the mean of its divisors is an integer number (7926850383).

Almost surely, 2^21138267686 is an apocalyptic number.

21138267686 is a deficient number, since it is larger than the sum of its proper divisors (10569133846).

21138267686 is a wasteful number, since it uses less digits than its factorization.

21138267686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10569133845.

The product of its digits is 1161216, while the sum is 50.

The spelling of 21138267686 in words is "twenty-one billion, one hundred thirty-eight million, two hundred sixty-seven thousand, six hundred eighty-six".