21047782100 has 18 divisors (see below), whose sum is σ = 45673687374. Its totient is φ = 8419112800.

The previous prime is 21047782087. The next prime is 21047782111. The reversal of 21047782100 is 128774012.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 6463838404 + 14583943696 = 80398^2 + 120764^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 105238811 + ... + 105239010.

Almost surely, 2^21047782100 is an apocalyptic number.

21047782100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21047782100 is an abundant number, since it is smaller than the sum of its proper divisors (24625905274).

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

21047782100 is a wasteful number, since it uses less digits than its factorization.

21047782100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210477835 (or 210477828 counting only the distinct ones).

The product of its (nonzero) digits is 6272, while the sum is 32.

The spelling of 21047782100 in words is "twenty-one billion, forty-seven million, seven hundred eighty-two thousand, one hundred".