21591694 has 4 divisors (see below), whose sum is σ = 32387544. Its totient is φ = 10795846.

The previous prime is 21591653. The next prime is 21591697. The reversal of 21591694 is 49619512.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21591697) by changing a digit.

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, 5397922 + ... + 5397925.

It is an arithmetic number, because the mean of its divisors is an integer number (8096886).

Almost surely, 2^21591694 is an apocalyptic number.

21591694 is a deficient number, since it is larger than the sum of its proper divisors (10795850).

21591694 is a wasteful number, since it uses less digits than its factorization.

21591694 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10795849.

The product of its digits is 19440, while the sum is 37.

The square root of 21591694 is about 4646.6863462041. The cubic root of 21591694 is about 278.4596281838.

The spelling of 21591694 in words is "twenty-one million, five hundred ninety-one thousand, six hundred ninety-four".