21006422 has 4 divisors (see below), whose sum is σ = 31509636. Its totient is φ = 10503210.

The previous prime is 21006421. The next prime is 21006431. The reversal of 21006422 is 22460012.

It is a semiprime because it is the product of two primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21006422.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21006421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5251604 + ... + 5251607.

It is an arithmetic number, because the mean of its divisors is an integer number (7877409).

Almost surely, 2^21006422 is an apocalyptic number.

21006422 is a deficient number, since it is larger than the sum of its proper divisors (10503214).

21006422 is a wasteful number, since it uses less digits than its factorization.

21006422 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10503213.

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 21006422 is about 4583.2763390396. The cubic root of 21006422 is about 275.9205382814.

Adding to 21006422 its reverse (22460012), we get a palindrome (43466434).

The spelling of 21006422 in words is "twenty-one million, six thousand, four hundred twenty-two".