21540391850 has 24 divisors (see below), whose sum is σ = 41357555328. Its totient is φ = 8338215600.

The previous prime is 21540391843. The next prime is 21540391867. The reversal of 21540391850 is 5819304512.

It is a happy number.

It is a Curzon 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, 6946964 + ... + 6950063.

It is an arithmetic number, because the mean of its divisors is an integer number (1723231472).

Almost surely, 2^21540391850 is an apocalyptic number.

21540391850 is a deficient number, since it is larger than the sum of its proper divisors (19817163478).

21540391850 is a wasteful number, since it uses less digits than its factorization.

21540391850 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13897070 (or 13897065 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 38.

The spelling of 21540391850 in words is "twenty-one billion, five hundred forty million, three hundred ninety-one thousand, eight hundred fifty".