20821694 has 4 divisors (see below), whose sum is σ = 31232544. Its totient is φ = 10410846.

The previous prime is 20821667. The next prime is 20821709. The reversal of 20821694 is 49612802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 49612802 = 2 ⋅24806401.

It is a self number, because there is not a number n which added to its sum of digits gives 20821694.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 5205422 + ... + 5205425.

It is an arithmetic number, because the mean of its divisors is an integer number (7808136).

Almost surely, 2^20821694 is an apocalyptic number.

20821694 is a deficient number, since it is larger than the sum of its proper divisors (10410850).

20821694 is a wasteful number, since it uses less digits than its factorization.

20821694 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10410849.

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 20821694 is about 4563.0794426571. The cubic root of 20821694 is about 275.1093515528.

The spelling of 20821694 in words is "twenty million, eight hundred twenty-one thousand, six hundred ninety-four".