21423006 has 48 divisors (see below), whose sum is σ = 50953968. Its totient is φ = 6451200.

The previous prime is 21422993. The next prime is 21423007. The reversal of 21423006 is 60032412.

It is a happy number.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21423006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21423007) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 50676 + ... + 51096.

It is an arithmetic number, because the mean of its divisors is an integer number (1061541).

Almost surely, 2^21423006 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21423006, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25476984).

21423006 is an abundant number, since it is smaller than the sum of its proper divisors (29530962).

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

21423006 is a wasteful number, since it uses less digits than its factorization.

21423006 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 697 (or 694 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 21423006 is about 4628.4993248352. The cubic root of 21423006 is about 277.7325637461.

Adding to 21423006 its reverse (60032412), we get a palindrome (81455418).

It can be divided in two parts, 214 and 23006, that added together give a triangular number (23220 = T₂₁₅).

The spelling of 21423006 in words is "twenty-one million, four hundred twenty-three thousand, six".