21981887534 has 4 divisors (see below), whose sum is σ = 32972831304. Its totient is φ = 10990943766.

The previous prime is 21981887527. The next prime is 21981887573. The reversal of 21981887534 is 43578818912.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21981887534.

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, 5495471882 + ... + 5495471885.

It is an arithmetic number, because the mean of its divisors is an integer number (8243207826).

Almost surely, 2^21981887534 is an apocalyptic number.

21981887534 is a deficient number, since it is larger than the sum of its proper divisors (10990943770).

21981887534 is a wasteful number, since it uses less digits than its factorization.

21981887534 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10990943769.

The product of its digits is 3870720, while the sum is 56.

The spelling of 21981887534 in words is "twenty-one billion, nine hundred eighty-one million, eight hundred eighty-seven thousand, five hundred thirty-four".