21359640638 has 16 divisors (see below), whose sum is σ = 36618582624. Its totient is φ = 9153617760.

The previous prime is 21359640629. The next prime is 21359640703. The reversal of 21359640638 is 83604695312.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21359640592 and 21359640601.

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, 323456 + ... + 383852.

It is an arithmetic number, because the mean of its divisors is an integer number (2288661414).

Almost surely, 2^21359640638 is an apocalyptic number.

21359640638 is a deficient number, since it is larger than the sum of its proper divisors (15258941986).

21359640638 is a wasteful number, since it uses less digits than its factorization.

21359640638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85667.

The product of its (nonzero) digits is 933120, while the sum is 47.

The spelling of 21359640638 in words is "twenty-one billion, three hundred fifty-nine million, six hundred forty thousand, six hundred thirty-eight".