21723520212 has 36 divisors (see below), whose sum is σ = 55125921396. Its totient is φ = 7212994560.

The previous prime is 21723520199. The next prime is 21723520223. The reversal of 21723520212 is 21202532712.

21723520212 is a `hidden beast` number, since 217 + 235 + 2 + 0 + 212 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 16930173456 + 4793346756 = 130116^2 + 69234^2 .

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

It is a super-2 number, since 2×21723520212² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1164739 + ... + 1183242.

Almost surely, 2^21723520212 is an apocalyptic number.

It is an amenable number.

21723520212 is an abundant number, since it is smaller than the sum of its proper divisors (33402401184).

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

21723520212 is a wasteful number, since it uses less digits than its factorization.

21723520212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2348248 (or 2348243 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 27.

The spelling of 21723520212 in words is "twenty-one billion, seven hundred twenty-three million, five hundred twenty thousand, two hundred twelve".