21253394 has 4 divisors (see below), whose sum is σ = 31880094. Its totient is φ = 10626696.

The previous prime is 21253373. The next prime is 21253423. The reversal of 21253394 is 49335212.

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., 14938225 + 6315169 = 3865^2 + 2513^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5313347 + ... + 5313350.

Almost surely, 2^21253394 is an apocalyptic number.

21253394 is a deficient number, since it is larger than the sum of its proper divisors (10626700).

21253394 is a wasteful number, since it uses less digits than its factorization.

21253394 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10626699.

The product of its digits is 6480, while the sum is 29.

The square root of 21253394 is about 4610.1403449353. The cubic root of 21253394 is about 276.9976584057.

The spelling of 21253394 in words is "twenty-one million, two hundred fifty-three thousand, three hundred ninety-four".