21187700 has 18 divisors (see below), whose sum is σ = 45977526. Its totient is φ = 8475040.

The previous prime is 21187697. The next prime is 21187753. The reversal of 21187700 is 778112.

It can be written as a sum of positive squares in 3 ways, for example, as 357604 + 20830096 = 598^2 + 4564^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21187700.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 105839 + ... + 106038.

It is an arithmetic number, because the mean of its divisors is an integer number (2554307).

Almost surely, 2^21187700 is an apocalyptic number.

21187700 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21187700 is an abundant number, since it is smaller than the sum of its proper divisors (24789826).

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

21187700 is a wasteful number, since it uses less digits than its factorization.

21187700 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211891 (or 211884 counting only the distinct ones).

The product of its (nonzero) digits is 784, while the sum is 26.

The square root of 21187700 is about 4603.0098848471. The cubic root of 21187700 is about 276.7119649705.

The spelling of 21187700 in words is "twenty-one million, one hundred eighty-seven thousand, seven hundred".