21305869638 has 16 divisors (see below), whose sum is σ = 42613251120. Its totient is φ = 7101704576.

The previous prime is 21305869619. The next prime is 21305869643. The reversal of 21305869638 is 83696850312.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 213706 + ... + 297122.

It is an arithmetic number, because the mean of its divisors is an integer number (2663328195).

Almost surely, 2^21305869638 is an apocalyptic number.

21305869638 is an abundant number, since it is smaller than the sum of its proper divisors (21307381482).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21305869638 is a wasteful number, since it uses less digits than its factorization.

21305869638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125991.

The product of its (nonzero) digits is 1866240, while the sum is 51.

The spelling of 21305869638 in words is "twenty-one billion, three hundred five million, eight hundred sixty-nine thousand, six hundred thirty-eight".