21509453166 has 16 divisors (see below), whose sum is σ = 43074567504. Its totient is φ = 7160540864.

The previous prime is 21509453153. The next prime is 21509453221. The reversal of 21509453166 is 66135490512.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2314191 + ... + 2323466.

It is an arithmetic number, because the mean of its divisors is an integer number (2692160469).

Almost surely, 2^21509453166 is an apocalyptic number.

21509453166 is an abundant number, since it is smaller than the sum of its proper divisors (21565114338).

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

21509453166 is a wasteful number, since it uses less digits than its factorization.

21509453166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4638435.

The product of its (nonzero) digits is 194400, while the sum is 42.

The spelling of 21509453166 in words is "twenty-one billion, five hundred nine million, four hundred fifty-three thousand, one hundred sixty-six".