20688890 has 16 divisors (see below), whose sum is σ = 38524680. Its totient is φ = 7990080.

The previous prime is 20688869. The next prime is 20688907. The reversal of 20688890 is 9888602.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 13010449 + 7678441 = 3607^2 + 2771^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35381 + ... + 35960.

Almost surely, 2^20688890 is an apocalyptic number.

20688890 is a deficient number, since it is larger than the sum of its proper divisors (17835790).

20688890 is a wasteful number, since it uses less digits than its factorization.

20688890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71377.

The product of its (nonzero) digits is 55296, while the sum is 41.

The square root of 20688890 is about 4548.5041497178. The cubic root of 20688890 is about 274.5232068749.

The spelling of 20688890 in words is "twenty million, six hundred eighty-eight thousand, eight hundred ninety".