21425100 has 72 divisors (see below), whose sum is σ = 65652048. Its totient is φ = 5376000.

The previous prime is 21425099. The next prime is 21425147. The reversal of 21425100 is 152412.

21425100 = 1633² + 1634² + ... + 1640².

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21425100.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3000 + ... + 7200.

It is an arithmetic number, because the mean of its divisors is an integer number (911834).

Almost surely, 2^21425100 is an apocalyptic number.

21425100 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 21425100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32826024).

21425100 is an abundant number, since it is smaller than the sum of its proper divisors (44226948).

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

21425100 is a wasteful number, since it uses less digits than its factorization.

21425100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4235 (or 4228 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 15.

The square root of 21425100 is about 4628.7255265354. The cubic root of 21425100 is about 277.7416124768.

Adding to 21425100 its reverse (152412), we get a palindrome (21577512).

The spelling of 21425100 in words is "twenty-one million, four hundred twenty-five thousand, one hundred".