21404402 has 4 divisors (see below), whose sum is σ = 32106606. Its totient is φ = 10702200.

The previous prime is 21404399. The next prime is 21404413. The reversal of 21404402 is 20440412.

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., 14280841 + 7123561 = 3779^2 + 2669^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5351099 + ... + 5351102.

Almost surely, 2^21404402 is an apocalyptic number.

21404402 is a deficient number, since it is larger than the sum of its proper divisors (10702204).

21404402 is a wasteful number, since it uses less digits than its factorization.

21404402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10702203.

The product of its (nonzero) digits is 256, while the sum is 17.

The square root of 21404402 is about 4626.4891656633. The cubic root of 21404402 is about 277.6521450128.

Adding to 21404402 its reverse (20440412), we get a palindrome (41844814).

The spelling of 21404402 in words is "twenty-one million, four hundred four thousand, four hundred two".