21001009988 has 12 divisors (see below), whose sum is σ = 42002020032. Its totient is φ = 9000432840.

The previous prime is 21001009973. The next prime is 21001009999. The reversal of 21001009988 is 88990010012.

21001009988 is an admirable number.

It is a hoax number, since the sum of its digits (38) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 375018008 + ... + 375018063.

It is an arithmetic number, because the mean of its divisors is an integer number (3500168336).

Almost surely, 2^21001009988 is an apocalyptic number.

21001009988 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21001009988 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21001009988 is a wasteful number, since it uses less digits than its factorization.

21001009988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 750036082 (or 750036080 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 38.

The spelling of 21001009988 in words is "twenty-one billion, one million, nine thousand, nine hundred eighty-eight".