21205473759 has 8 divisors (see below), whose sum is σ = 31415516720. Its totient is φ = 14136982488.

The previous prime is 21205473743. The next prime is 21205473767. The reversal of 21205473759 is 95737450212.

It is a happy number.

21205473759 is a `hidden beast` number, since 2 + 1 + 20 + 547 + 37 + 59 = 666.

It is not a de Polignac number, because 21205473759 - 2⁴ = 21205473743 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21205473739) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 392693932 + ... + 392693985.

It is an arithmetic number, because the mean of its divisors is an integer number (3926939590).

Almost surely, 2^21205473759 is an apocalyptic number.

21205473759 is a deficient number, since it is larger than the sum of its proper divisors (10210042961).

21205473759 is an equidigital number, since it uses as much as digits as its factorization.

21205473759 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 785387926 (or 785387920 counting only the distinct ones).

The product of its (nonzero) digits is 529200, while the sum is 45.

The spelling of 21205473759 in words is "twenty-one billion, two hundred five million, four hundred seventy-three thousand, seven hundred fifty-nine".