20661638 has 8 divisors (see below), whose sum is σ = 31053288. Its totient is φ = 10310544.

The previous prime is 20661631. The next prime is 20661643. The reversal of 20661638 is 83616602.

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 (20661631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8831 + ... + 10922.

It is an arithmetic number, because the mean of its divisors is an integer number (3881661).

Almost surely, 2^20661638 is an apocalyptic number.

20661638 is a deficient number, since it is larger than the sum of its proper divisors (10391650).

20661638 is a wasteful number, since it uses less digits than its factorization.

20661638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20278.

The product of its (nonzero) digits is 10368, while the sum is 32.

The square root of 20661638 is about 4545.5074524194. The cubic root of 20661638 is about 274.4026172943.

The spelling of 20661638 in words is "twenty million, six hundred sixty-one thousand, six hundred thirty-eight".