21650181988 has 24 divisors (see below), whose sum is σ = 38082713760. Its totient is φ = 10769486400.

The previous prime is 21650181899. The next prime is 21650182013. The reversal of 21650181988 is 88918105612.

It is a super-2 number, since 2×21650181988² (a number of 21 digits) contains 22 as substring.

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 in 7 ways as a sum of consecutive naturals, for example, 1164163 + ... + 1182613.

It is an arithmetic number, because the mean of its divisors is an integer number (1586779740).

Almost surely, 2^21650181988 is an apocalyptic number.

It is an amenable number.

21650181988 is a deficient number, since it is larger than the sum of its proper divisors (16432531772).

21650181988 is a wasteful number, since it uses less digits than its factorization.

21650181988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19947 (or 19945 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 49.

The spelling of 21650181988 in words is "twenty-one billion, six hundred fifty million, one hundred eighty-one thousand, nine hundred eighty-eight".