21665201338 has 16 divisors (see below), whose sum is σ = 35981286624. Its totient is φ = 9700835760.

The previous prime is 21665201329. The next prime is 21665201423. The reversal of 21665201338 is 83310256612.

It is a junction number, because it is equal to n+sod(n) for n = 21665201297 and 21665201306.

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, 7347645 + ... + 7350592.

It is an arithmetic number, because the mean of its divisors is an integer number (2248830414).

Almost surely, 2^21665201338 is an apocalyptic number.

21665201338 is a deficient number, since it is larger than the sum of its proper divisors (14316085286).

21665201338 is a wasteful number, since it uses less digits than its factorization.

21665201338 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14698317.

The product of its (nonzero) digits is 51840, while the sum is 37.

The spelling of 21665201338 in words is "twenty-one billion, six hundred sixty-five million, two hundred one thousand, three hundred thirty-eight".