21390422 has 8 divisors (see below), whose sum is σ = 32397456. Its totient is φ = 10591272.

The previous prime is 21390389. The next prime is 21390427. The reversal of 21390422 is 22409312.

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 (21390427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 51713 + ... + 52124.

It is an arithmetic number, because the mean of its divisors is an integer number (4049682).

Almost surely, 2^21390422 is an apocalyptic number.

21390422 is a deficient number, since it is larger than the sum of its proper divisors (11007034).

21390422 is a wasteful number, since it uses less digits than its factorization.

21390422 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103942.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21390422 is about 4624.9780540020. The cubic root of 21390422 is about 277.5916835812.

Adding to 21390422 its reverse (22409312), we get a palindrome (43799734).

It can be divided in two parts, 21390 and 422, that added together give a palindrome (21812).

The spelling of 21390422 in words is "twenty-one million, three hundred ninety thousand, four hundred twenty-two".