21001212008 has 16 divisors (see below), whose sum is σ = 45002597280. Its totient is φ = 9000519408.

The previous prime is 21001212007. The next prime is 21001212017. The reversal of 21001212008 is 80021210012.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21001212007) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 187510766 + ... + 187510877.

It is an arithmetic number, because the mean of its divisors is an integer number (2812662330).

Almost surely, 2^21001212008 is an apocalyptic number.

21001212008 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21001212008 is an abundant number, since it is smaller than the sum of its proper divisors (24001385272).

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

21001212008 is a wasteful number, since it uses less digits than its factorization.

21001212008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 375021656 (or 375021652 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 17.

The spelling of 21001212008 in words is "twenty-one billion, one million, two hundred twelve thousand, eight".