21297979798 has 4 divisors (see below), whose sum is σ = 31946969700. Its totient is φ = 10648989898.

The previous prime is 21297979777. The next prime is 21297979819. The reversal of 21297979798 is 89797979212.

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

It is an interprime number because it is at equal distance from previous prime (21297979777) and next prime (21297979819).

It is a super-3 number, since 3×21297979798³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5324494948 + ... + 5324494951.

It is an arithmetic number, because the mean of its divisors is an integer number (7986742425).

Almost surely, 2^21297979798 is an apocalyptic number.

21297979798 is a deficient number, since it is larger than the sum of its proper divisors (10648989902).

21297979798 is a wasteful number, since it uses less digits than its factorization.

21297979798 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10648989901.

The product of its digits is 72013536, while the sum is 70.

The spelling of 21297979798 in words is "twenty-one billion, two hundred ninety-seven million, nine hundred seventy-nine thousand, seven hundred ninety-eight".