20857994 has 4 divisors (see below), whose sum is σ = 31286994. Its totient is φ = 10428996.

The previous prime is 20857981. The next prime is 20857999. The reversal of 20857994 is 49975802.

It is a happy number.

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

It can be written as a sum of positive squares in only one way, i.e., 20839225 + 18769 = 4565^2 + 137^2 .

It is not an unprimeable number, because it can be changed into a prime (20857999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5214497 + ... + 5214500.

Almost surely, 2^20857994 is an apocalyptic number.

20857994 is a deficient number, since it is larger than the sum of its proper divisors (10429000).

20857994 is a wasteful number, since it uses less digits than its factorization.

20857994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10428999.

The product of its (nonzero) digits is 181440, while the sum is 44.

The square root of 20857994 is about 4567.0552876005. The cubic root of 20857994 is about 275.2691315670.

The spelling of 20857994 in words is "twenty million, eight hundred fifty-seven thousand, nine hundred ninety-four".