21425580 has 96 divisors (see below), whose sum is σ = 72737280. Its totient is φ = 5192640.

The previous prime is 21425549. The next prime is 21425587. The reversal of 21425580 is 8552412.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21425587) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4137 + ... + 7743.

It is an arithmetic number, because the mean of its divisors is an integer number (757680).

Almost surely, 2^21425580 is an apocalyptic number.

21425580 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 21425580, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36368640).

21425580 is an abundant number, since it is smaller than the sum of its proper divisors (51311700).

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

21425580 is a wasteful number, since it uses less digits than its factorization.

21425580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3636 (or 3628 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 27.

The square root of 21425580 is about 4628.7773763706. Note that the first 3 decimals coincide. The cubic root of 21425580 is about 277.7436866014.

Adding to 21425580 its reverse (8552412), we get a palindrome (29977992).

The spelling of 21425580 in words is "twenty-one million, four hundred twenty-five thousand, five hundred eighty".