21121502166 has 112 divisors (see below), whose sum is σ = 48449035008. Its totient is φ = 6901297200.

The previous prime is 21121502123. The next prime is 21121502183. The reversal of 21121502166 is 66120512112.

21121502166 is a `hidden beast` number, since 21 + 121 + 502 + 16 + 6 = 666.

It is a super-2 number, since 2×21121502166² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 21841815 + ... + 21842781.

Almost surely, 2^21121502166 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21121502166, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24224517504).

21121502166 is an abundant number, since it is smaller than the sum of its proper divisors (27327532842).

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

21121502166 is an equidigital number, since it uses as much as digits as its factorization.

21121502166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1269 (or 1254 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The spelling of 21121502166 in words is "twenty-one billion, one hundred twenty-one million, five hundred two thousand, one hundred sixty-six".