21000120008 has 64 divisors (see below), whose sum is σ = 47956008960. Its totient is φ = 8425555776.

The previous prime is 21000119999. The next prime is 21000120013. The reversal of 21000120008 is 80002100012.

It is a Harshad number since it is a multiple of its sum of digits (14).

It is a junction number, because it is equal to n+sod(n) for n = 21000119974 and 21000120001.

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 15 ways as a sum of consecutive naturals, for example, 112916 + ... + 233987.

It is an arithmetic number, because the mean of its divisors is an integer number (749312640).

Almost surely, 2^21000120008 is an apocalyptic number.

21000120008 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21000120008 is an abundant number, since it is smaller than the sum of its proper divisors (26955888952).

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

21000120008 is a wasteful number, since it uses less digits than its factorization.

21000120008 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 346986 (or 346982 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

The spelling of 21000120008 in words is "twenty-one billion, one hundred twenty thousand, eight".