21081694 has 8 divisors (see below), whose sum is σ = 31714200. Its totient is φ = 10510296.

The previous prime is 21081691. The next prime is 21081707. The reversal of 21081694 is 49618012.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21081691) 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 in 3 ways as a sum of consecutive naturals, for example, 14404 + ... + 15799.

It is an arithmetic number, because the mean of its divisors is an integer number (3964275).

Almost surely, 2^21081694 is an apocalyptic number.

21081694 is a deficient number, since it is larger than the sum of its proper divisors (10632506).

21081694 is a wasteful number, since it uses less digits than its factorization.

21081694 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30554.

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 21081694 is about 4591.4805890911. The cubic root of 21081694 is about 276.2497127410.

The spelling of 21081694 in words is "twenty-one million, eighty-one thousand, six hundred ninety-four".