21390430 has 8 divisors (see below), whose sum is σ = 38502792. Its totient is φ = 8556168.

The previous prime is 21390427. The next prime is 21390433. The reversal of 21390430 is 3409312.

It is an interprime number because it is at equal distance from previous prime (21390427) and next prime (21390433).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21390433) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1069512 + ... + 1069531.

It is an arithmetic number, because the mean of its divisors is an integer number (4812849).

Almost surely, 2^21390430 is an apocalyptic number.

21390430 is a deficient number, since it is larger than the sum of its proper divisors (17112362).

21390430 is a wasteful number, since it uses less digits than its factorization.

21390430 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2139050.

The product of its (nonzero) digits is 648, while the sum is 22.

The square root of 21390430 is about 4624.9789188709. The cubic root of 21390430 is about 277.5917181876.

Adding to 21390430 its reverse (3409312), we get a palindrome (24799742).

The spelling of 21390430 in words is "twenty-one million, three hundred ninety thousand, four hundred thirty".