21099609988 has 12 divisors (see below), whose sum is σ = 36935925712. Its totient is φ = 10546488360.

The previous prime is 21099609983. The next prime is 21099610003. The reversal of 21099609988 is 88990699012.

It is not an unprimeable number, because it can be changed into a prime (21099609983) 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, 814818 + ... + 840313.

Almost surely, 2^21099609988 is an apocalyptic number.

It is an amenable number.

21099609988 is a deficient number, since it is larger than the sum of its proper divisors (15836315724).

21099609988 is a wasteful number, since it uses less digits than its factorization.

21099609988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1658322 (or 1658320 counting only the distinct ones).

The product of its (nonzero) digits is 5038848, while the sum is 61.

The spelling of 21099609988 in words is "twenty-one billion, ninety-nine million, six hundred nine thousand, nine hundred eighty-eight".