21205473718 has 48 divisors (see below), whose sum is σ = 37673841744. Its totient is φ = 8825423040.

The previous prime is 21205473713. The next prime is 21205473739. The reversal of 21205473718 is 81737450212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21205473713) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4610596 + ... + 4615192.

It is an arithmetic number, because the mean of its divisors is an integer number (784871703).

Almost surely, 2^21205473718 is an apocalyptic number.

21205473718 is a deficient number, since it is larger than the sum of its proper divisors (16468368026).

21205473718 is a wasteful number, since it uses less digits than its factorization.

21205473718 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4877 (or 4750 counting only the distinct ones).

The product of its (nonzero) digits is 94080, while the sum is 40.

The spelling of 21205473718 in words is "twenty-one billion, two hundred five million, four hundred seventy-three thousand, seven hundred eighteen".