21004550440 has 32 divisors (see below), whose sum is σ = 47521361160. Its totient is φ = 8355398400.

The previous prime is 21004550377. The next prime is 21004550467. The reversal of 21004550440 is 4405540012.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 8252268964 + 12752281476 = 90842^2 + 112926^2 .

It is a super-2 number, since 2×21004550440² (a number of 21 digits) contains 22 as substring.

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, 1443351 + ... + 1457830.

Almost surely, 2^21004550440 is an apocalyptic number.

21004550440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21004550440 is an abundant number, since it is smaller than the sum of its proper divisors (26516810720).

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

21004550440 is a wasteful number, since it uses less digits than its factorization.

21004550440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2901373 (or 2901369 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 25.

The spelling of 21004550440 in words is "twenty-one billion, four million, five hundred fifty thousand, four hundred forty".