21680699378 has 18 divisors (see below), whose sum is σ = 35219497959. Its totient is φ = 10005227232.

The previous prime is 21680699371. The next prime is 21680699387. The reversal of 21680699378 is 87399608612.

It can be written as a sum of positive squares in 5 ways, for example, as 5802935329 + 15877764049 = 76177^2 + 126007^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=104117.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21680699371) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 2703038 + ... + 2711046.

Almost surely, 2^21680699378 is an apocalyptic number.

21680699378 is a deficient number, since it is larger than the sum of its proper divisors (13538798581).

21680699378 is an frugal number, since it uses more digits than its factorization.

21680699378 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16046 (or 8024 counting only the distinct ones).

The product of its (nonzero) digits is 7838208, while the sum is 59.

The spelling of 21680699378 in words is "twenty-one billion, six hundred eighty million, six hundred ninety-nine thousand, three hundred seventy-eight".