21465221220 has 36 divisors (see below), whose sum is σ = 65111171580. Its totient is φ = 5724058944.

The previous prime is 21465221161. The next prime is 21465221249. The reversal of 21465221220 is 2212256412.

21465221220 is a `hidden beast` number, since 2 + 1 + 4 + 652 + 2 + 1 + 2 + 2 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 4743627876 + 16721593344 = 68874^2 + 129312^2 .

It is a tau number, because it is divible by the number of its divisors (36).

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 11 ways as a sum of consecutive naturals, for example, 59625435 + ... + 59625794.

It is an arithmetic number, because the mean of its divisors is an integer number (1808643655).

Almost surely, 2^21465221220 is an apocalyptic number.

21465221220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21465221220 is an abundant number, since it is smaller than the sum of its proper divisors (43645950360).

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

21465221220 is a wasteful number, since it uses less digits than its factorization.

21465221220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 119251244 (or 119251239 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

Adding to 21465221220 its reverse (2212256412), we get a palindrome (23677477632).

The spelling of 21465221220 in words is "twenty-one billion, four hundred sixty-five million, two hundred twenty-one thousand, two hundred twenty".