21887644718 has 4 divisors (see below), whose sum is σ = 32831467080. Its totient is φ = 10943822358.

The previous prime is 21887644697. The next prime is 21887644787. The reversal of 21887644718 is 81744678812.

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 (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5471911178 + ... + 5471911181.

It is an arithmetic number, because the mean of its divisors is an integer number (8207866770).

Almost surely, 2^21887644718 is an apocalyptic number.

21887644718 is a deficient number, since it is larger than the sum of its proper divisors (10943822362).

21887644718 is a wasteful number, since it uses less digits than its factorization.

21887644718 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10943822361.

The product of its digits is 4816896, while the sum is 56.

The spelling of 21887644718 in words is "twenty-one billion, eight hundred eighty-seven million, six hundred forty-four thousand, seven hundred eighteen".