21208817548 has 6 divisors (see below), whose sum is σ = 37115430716. Its totient is φ = 10604408772.

The previous prime is 21208817543. The next prime is 21208817549. The reversal of 21208817548 is 84571880212.

It is a junction number, because it is equal to n+sod(n) for n = 21208817498 and 21208817507.

It is not an unprimeable number, because it can be changed into a prime (21208817543) 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 as a sum of consecutive naturals, namely, 2651102190 + ... + 2651102197.

Almost surely, 2^21208817548 is an apocalyptic number.

It is an amenable number.

21208817548 is a deficient number, since it is larger than the sum of its proper divisors (15906613168).

21208817548 is a wasteful number, since it uses less digits than its factorization.

21208817548 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5302204391 (or 5302204389 counting only the distinct ones).

The product of its (nonzero) digits is 286720, while the sum is 46.

The spelling of 21208817548 in words is "twenty-one billion, two hundred eight million, eight hundred seventeen thousand, five hundred forty-eight".