21725100 has 108 divisors (see below), whose sum is σ = 69058080. Its totient is φ = 5712000.

The previous prime is 21725063. The next prime is 21725101. The reversal of 21725100 is 152712.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21725101) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 90781 + ... + 91019.

Almost surely, 2^21725100 is an apocalyptic number.

21725100 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 21725100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34529040).

21725100 is an abundant number, since it is smaller than the sum of its proper divisors (47332980).

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

21725100 is a wasteful number, since it uses less digits than its factorization.

21725100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 360 (or 350 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 18.

The square root of 21725100 is about 4661.0192018485. The cubic root of 21725100 is about 279.0319460857.

Adding to 21725100 its reverse (152712), we get a palindrome (21877812).

The spelling of 21725100 in words is "twenty-one million, seven hundred twenty-five thousand, one hundred".