21000198980 has 12 divisors (see below), whose sum is σ = 44100417900. Its totient is φ = 8400079584.

The previous prime is 21000198979. The next prime is 21000199001. The reversal of 21000198980 is 8989100012.

It can be written as a sum of positive squares in 2 ways, for example, as 12325884484 + 8674314496 = 111022^2 + 93136^2 .

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, 525004955 + ... + 525004994.

It is an arithmetic number, because the mean of its divisors is an integer number (3675034825).

Almost surely, 2^21000198980 is an apocalyptic number.

21000198980 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21000198980 is an abundant number, since it is smaller than the sum of its proper divisors (23100218920).

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

21000198980 is a wasteful number, since it uses less digits than its factorization.

21000198980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1050009958 (or 1050009956 counting only the distinct ones).

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

Adding to 21000198980 its reverse (8989100012), we get a palindrome (29989298992).

The spelling of 21000198980 in words is "twenty-one billion, one hundred ninety-eight thousand, nine hundred eighty".