21244402 has 4 divisors (see below), whose sum is σ = 31866606. Its totient is φ = 10622200.

The previous prime is 21244369. The next prime is 21244417. The reversal of 21244402 is 20444212.

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

It can be written as a sum of positive squares in only one way, i.e., 21242881 + 1521 = 4609^2 + 39^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21244402.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 5311099 + ... + 5311102.

Almost surely, 2^21244402 is an apocalyptic number.

21244402 is a deficient number, since it is larger than the sum of its proper divisors (10622204).

21244402 is a wasteful number, since it uses less digits than its factorization.

21244402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10622203.

The product of its (nonzero) digits is 512, while the sum is 19.

The square root of 21244402 is about 4609.1650003010. The cubic root of 21244402 is about 276.9585883433.

Adding to 21244402 its reverse (20444212), we get a palindrome (41688614).

The spelling of 21244402 in words is "twenty-one million, two hundred forty-four thousand, four hundred two".