21521100002 has 4 divisors (see below), whose sum is σ = 32281650006. Its totient is φ = 10760550000.

The previous prime is 21521099983. The next prime is 21521100031. The reversal of 21521100002 is 20000112512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 16718748601 + 4802351401 = 129301^2 + 69299^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21521100002.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5380274999 + ... + 5380275002.

Almost surely, 2^21521100002 is an apocalyptic number.

21521100002 is a deficient number, since it is larger than the sum of its proper divisors (10760550004).

21521100002 is a wasteful number, since it uses less digits than its factorization.

21521100002 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10760550003.

The product of its (nonzero) digits is 40, while the sum is 14.

Adding to 21521100002 its reverse (20000112512), we get a palindrome (41521212514).

The spelling of 21521100002 in words is "twenty-one billion, five hundred twenty-one million, one hundred thousand, two".