21395863634 has 16 divisors (see below), whose sum is σ = 34117433280. Its totient is φ = 10034535600.

The previous prime is 21395863631. The next prime is 21395863637. The reversal of 21395863634 is 43636859312.

21395863634 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (21395863631) and next prime (21395863637).

It is not an unprimeable number, because it can be changed into a prime (21395863631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2783534 + ... + 2791209.

It is an arithmetic number, because the mean of its divisors is an integer number (2132339580).

Almost surely, 2^21395863634 is an apocalyptic number.

21395863634 is a deficient number, since it is larger than the sum of its proper divisors (12721569646).

21395863634 is a wasteful number, since it uses less digits than its factorization.

21395863634 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5574865.

The product of its digits is 2799360, while the sum is 50.

The spelling of 21395863634 in words is "twenty-one billion, three hundred ninety-five million, eight hundred sixty-three thousand, six hundred thirty-four".