21099003856 has 20 divisors (see below), whose sum is σ = 46719223072. Its totient is φ = 9042430176.

The previous prime is 21099003847. The next prime is 21099003857. The reversal of 21099003856 is 65830099012.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21099003857) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 94191870 + ... + 94192093.

Almost surely, 2^21099003856 is an apocalyptic number.

It is an amenable number.

21099003856 is an abundant number, since it is smaller than the sum of its proper divisors (25620219216).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21099003856 is a wasteful number, since it uses less digits than its factorization.

21099003856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188383978 (or 188383972 counting only the distinct ones).

The product of its (nonzero) digits is 116640, while the sum is 43.

The spelling of 21099003856 in words is "twenty-one billion, ninety-nine million, three thousand, eight hundred fifty-six".