21138542882 has 4 divisors (see below), whose sum is σ = 31707814326. Its totient is φ = 10569271440.

The previous prime is 21138542861. The next prime is 21138542923. The reversal of 21138542882 is 28824583112.

It is a Cunningham number, because it is equal to 145391²+1.

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

It can be written as a sum of positive squares in only one way, i.e., 21138542881 + 1 = 145391^2 + 1^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5284635719 + ... + 5284635722.

Almost surely, 2^21138542882 is an apocalyptic number.

21138542882 is a deficient number, since it is larger than the sum of its proper divisors (10569271444).

21138542882 is a wasteful number, since it uses less digits than its factorization.

21138542882 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10569271443.

The product of its digits is 245760, while the sum is 44.

The spelling of 21138542882 in words is "twenty-one billion, one hundred thirty-eight million, five hundred forty-two thousand, eight hundred eighty-two".