21621814 has 4 divisors (see below), whose sum is σ = 32432724. Its totient is φ = 10810906.

The previous prime is 21621793. The next prime is 21621823. The reversal of 21621814 is 41812612.

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

It is a congruent number.

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, 5405452 + ... + 5405455.

It is an arithmetic number, because the mean of its divisors is an integer number (8108181).

Almost surely, 2^21621814 is an apocalyptic number.

21621814 is a deficient number, since it is larger than the sum of its proper divisors (10810910).

21621814 is a wasteful number, since it uses less digits than its factorization.

21621814 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10810909.

The product of its digits is 768, while the sum is 25.

The square root of 21621814 is about 4649.9262359741. The cubic root of 21621814 is about 278.5890499733.

The spelling of 21621814 in words is "twenty-one million, six hundred twenty-one thousand, eight hundred fourteen".