20688946 has 4 divisors (see below), whose sum is σ = 31033422. Its totient is φ = 10344472.

The previous prime is 20688931. The next prime is 20688947. The reversal of 20688946 is 64988602.

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., 12215025 + 8473921 = 3495^2 + 2911^2 .

It is not an unprimeable number, because it can be changed into a prime (20688947) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5172235 + ... + 5172238.

Almost surely, 2^20688946 is an apocalyptic number.

20688946 is a deficient number, since it is larger than the sum of its proper divisors (10344476).

20688946 is a wasteful number, since it uses less digits than its factorization.

20688946 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10344475.

The product of its (nonzero) digits is 165888, while the sum is 43.

The square root of 20688946 is about 4548.5103055836. The cubic root of 20688946 is about 274.5234545648.

The spelling of 20688946 in words is "twenty million, six hundred eighty-eight thousand, nine hundred forty-six".