21504445402400 has 72 divisors (see below), whose sum is σ = 52663335932340. Its totient is φ = 8574643112960.

The previous prime is 21504445402379. The next prime is 21504445402409. The reversal of 21504445402400 is 420454440512.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 7085626429456 + 14418818972944 = 2661884^2 + 3797212^2 .

It is not an unprimeable number, because it can be changed into a prime (21504445402409) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 42144755 + ... + 42651954.

Almost surely, 2^{21504445402400} is an apocalyptic number.

21504445402400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21504445402400 is an abundant number, since it is smaller than the sum of its proper divisors (31158890529940).

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

21504445402400 is a wasteful number, since it uses less digits than its factorization.

21504445402400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84797046 (or 84797033 counting only the distinct ones).

The product of its (nonzero) digits is 102400, while the sum is 35.

Adding to 21504445402400 its reverse (420454440512), we get a palindrome (21924899842912).

The spelling of 21504445402400 in words is "twenty-one trillion, five hundred four billion, four hundred forty-five million, four hundred two thousand, four hundred".