21798100 has 18 divisors (see below), whose sum is σ = 47302094. Its totient is φ = 8719200.

The previous prime is 21798067. The next prime is 21798107. The reversal of 21798100 is 189712.

It can be written as a sum of positive squares in 3 ways, for example, as 138384 + 21659716 = 372^2 + 4654^2 .

It is a super-2 number, since 2×21798100² = 950314327220000, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21798107) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 108891 + ... + 109090.

Almost surely, 2^21798100 is an apocalyptic number.

21798100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21798100 is an abundant number, since it is smaller than the sum of its proper divisors (25503994).

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

21798100 is a wasteful number, since it uses less digits than its factorization.

21798100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 217995 (or 217988 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 21798100 is about 4668.8435398929. The cubic root of 21798100 is about 279.3441281510.

The spelling of 21798100 in words is "twenty-one million, seven hundred ninety-eight thousand, one hundred".