21308473775 has 12 divisors (see below), whose sum is σ = 26921047032. Its totient is φ = 16725140640.

The previous prime is 21308473721. The next prime is 21308473817. The reversal of 21308473775 is 57737480312.

It is a de Polignac number, because none of the positive numbers 2^k-21308473775 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8039609 + ... + 8042258.

It is an arithmetic number, because the mean of its divisors is an integer number (2243420586).

Almost surely, 2^21308473775 is an apocalyptic number.

21308473775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21308473775 is a deficient number, since it is larger than the sum of its proper divisors (5612573257).

21308473775 is a wasteful number, since it uses less digits than its factorization.

21308473775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16081930 (or 16081925 counting only the distinct ones).

The product of its (nonzero) digits is 987840, while the sum is 47.

The spelling of 21308473775 in words is "twenty-one billion, three hundred eight million, four hundred seventy-three thousand, seven hundred seventy-five".