21240204228 has 18 divisors (see below), whose sum is σ = 53690516334. Its totient is φ = 7080068064.

The previous prime is 21240204149. The next prime is 21240204229. The reversal of 21240204228 is 82240204212.

21240204228 is a `hidden beast` number, since 212 + 4 + 0 + 20 + 422 + 8 = 666.

It can be written as a sum of positive squares in only one way, i.e., 18504705024 + 2735499204 = 136032^2 + 52302^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a super-2 number, since 2×21240204228² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21240204229) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 295002801 + ... + 295002872.

It is an arithmetic number, because the mean of its divisors is an integer number (2982806463).

Almost surely, 2^21240204228 is an apocalyptic number.

It is an amenable number.

21240204228 is an abundant number, since it is smaller than the sum of its proper divisors (32450312106).

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

21240204228 is a wasteful number, since it uses less digits than its factorization.

21240204228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 590005683 (or 590005678 counting only the distinct ones).

The product of its (nonzero) digits is 4096, while the sum is 27.

The spelling of 21240204228 in words is "twenty-one billion, two hundred forty million, two hundred four thousand, two hundred twenty-eight".