21423402 has 192 divisors, whose sum is σ = 66044160. Its totient is φ = 4838400.

The previous prime is 21423377. The next prime is 21423403. The reversal of 21423402 is 20432412.

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 (21423403) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 522502 + ... + 522542.

It is an arithmetic number, because the mean of its divisors is an integer number (343980).

Almost surely, 2^21423402 is an apocalyptic number.

21423402 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 21423402, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33022080).

21423402 is an abundant number, since it is smaller than the sum of its proper divisors (44620758).

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

21423402 is a wasteful number, since it uses less digits than its factorization.

21423402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109 (or 106 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 21423402 is about 4628.5421030817. The cubic root of 21423402 is about 277.7342750126.

Adding to 21423402 its reverse (20432412), we get a palindrome (41855814).

The spelling of 21423402 in words is "twenty-one million, four hundred twenty-three thousand, four hundred two".