21290430 has 32 divisors (see below), whose sum is σ = 58397184. Its totient is φ = 4866336.

The previous prime is 21290419. The next prime is 21290441. The reversal of 21290430 is 3409212.

It is an interprime number because it is at equal distance from previous prime (21290419) and next prime (21290441).

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21290397 and 21290406.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 50482 + ... + 50901.

It is an arithmetic number, because the mean of its divisors is an integer number (1824912).

Almost surely, 2^21290430 is an apocalyptic number.

21290430 is an abundant number, since it is smaller than the sum of its proper divisors (37106754).

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

21290430 is a wasteful number, since it uses less digits than its factorization.

21290430 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101400.

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 21290430 is about 4614.1553940022. The cubic root of 21290430 is about 277.1584630286.

Adding to 21290430 its reverse (3409212), we get a palindrome (24699642).

The spelling of 21290430 in words is "twenty-one million, two hundred ninety thousand, four hundred thirty".