21225402 has 80 divisors (see below), whose sum is σ = 53282592. Its totient is φ = 6259680.

The previous prime is 21225397. The next prime is 21225403. The reversal of 21225402 is 20452212.

21225402 is a `hidden beast` number, since 2 + 122 + 540 + 2 = 666.

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 (21225403) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 76488 + ... + 76764.

Almost surely, 2^21225402 is an apocalyptic number.

21225402 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 21225402, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26641296).

21225402 is an abundant number, since it is smaller than the sum of its proper divisors (32057190).

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

21225402 is a wasteful number, since it uses less digits than its factorization.

21225402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 345 (or 336 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 21225402 is about 4607.1034284027. The cubic root of 21225402 is about 276.8759974452.

Adding to 21225402 its reverse (20452212), we get a palindrome (41677614).

The spelling of 21225402 in words is "twenty-one million, two hundred twenty-five thousand, four hundred two".