21204044240 has 40 divisors (see below), whose sum is σ = 52199371080. Its totient is φ = 7982698496.

The previous prime is 21204044227. The next prime is 21204044317. The reversal of 21204044240 is 4244040212.

It can be written as a sum of positive squares in 4 ways, for example, as 1779489856 + 19424554384 = 42184^2 + 139372^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a super-2 number, since 2×21204044240² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7794245 + ... + 7796964.

It is an arithmetic number, because the mean of its divisors is an integer number (1304984277).

Almost surely, 2^21204044240 is an apocalyptic number.

21204044240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21204044240 is an abundant number, since it is smaller than the sum of its proper divisors (30995326840).

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

21204044240 is a wasteful number, since it uses less digits than its factorization.

21204044240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15591239 (or 15591233 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 23.

Adding to 21204044240 its reverse (4244040212), we get a palindrome (25448084452).

The spelling of 21204044240 in words is "twenty-one billion, two hundred four million, forty-four thousand, two hundred forty".