21047400900 has 108 divisors (see below), whose sum is σ = 66061196292. Its totient is φ = 5605044480.

The previous prime is 21047400893. The next prime is 21047400929. The reversal of 21047400900 is 900474012.

It is a happy number.

21047400900 is a `hidden beast` number, since 210 + 47 + 400 + 9 + 0 + 0 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 428738436 + 20618662464 = 20706^2 + 143592^2 .

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 35 ways as a sum of consecutive naturals, for example, 665854 + ... + 696746.

Almost surely, 2^21047400900 is an apocalyptic number.

21047400900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21047400900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33030598146).

21047400900 is an abundant number, since it is smaller than the sum of its proper divisors (45013795392).

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

21047400900 is a wasteful number, since it uses less digits than its factorization.

21047400900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31670 (or 31660 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

Adding to 21047400900 its reverse (900474012), we get a palindrome (21947874912).

The spelling of 21047400900 in words is "twenty-one billion, forty-seven million, four hundred thousand, nine hundred".