21621695 has 4 divisors (see below), whose sum is σ = 25946040. Its totient is φ = 17297352.

The previous prime is 21621683. The next prime is 21621697. The reversal of 21621695 is 59612612.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21621695 - 2⁶ = 21621631 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21621697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2162165 + ... + 2162174.

It is an arithmetic number, because the mean of its divisors is an integer number (6486510).

Almost surely, 2^21621695 is an apocalyptic number.

21621695 is a deficient number, since it is larger than the sum of its proper divisors (4324345).

21621695 is an equidigital number, since it uses as much as digits as its factorization.

21621695 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4324344.

The product of its digits is 6480, while the sum is 32.

The square root of 21621695 is about 4649.9134400546. The cubic root of 21621695 is about 278.5885388820.

The spelling of 21621695 in words is "twenty-one million, six hundred twenty-one thousand, six hundred ninety-five".