21717700 has 36 divisors (see below), whose sum is σ = 48285972. Its totient is φ = 8473600.

The previous prime is 21717679. The next prime is 21717737. The reversal of 21717700 is 771712.

It can be written as a sum of positive squares in 6 ways, for example, as 1359556 + 20358144 = 1166^2 + 4512^2 .

It is a Harshad number since it is a multiple of its sum of digits (25).

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 11 ways as a sum of consecutive naturals, for example, 1452 + ... + 6748.

It is an arithmetic number, because the mean of its divisors is an integer number (1341277).

Almost surely, 2^21717700 is an apocalyptic number.

21717700 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 21717700, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24142986).

21717700 is an abundant number, since it is smaller than the sum of its proper divisors (26568272).

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

21717700 is a wasteful number, since it uses less digits than its factorization.

21717700 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5352 (or 5345 counting only the distinct ones).

The product of its (nonzero) digits is 686, while the sum is 25.

The square root of 21717700 is about 4660.2253164413. The cubic root of 21717700 is about 279.0002612160. Note that the first 3 decimals are identical.

The spelling of 21717700 in words is "twenty-one million, seven hundred seventeen thousand, seven hundred".