20686642 has 8 divisors (see below), whose sum is σ = 31615596. Its totient is φ = 10148112.

The previous prime is 20686621. The next prime is 20686661. The reversal of 20686642 is 24668602.

It can be written as a sum of positive squares in 2 ways, for example, as 16801801 + 3884841 = 4099^2 + 1971^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 20686598 and 20686607.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 97473 + ... + 97684.

Almost surely, 2^20686642 is an apocalyptic number.

20686642 is a deficient number, since it is larger than the sum of its proper divisors (10928954).

20686642 is a wasteful number, since it uses less digits than its factorization.

20686642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 195212.

The product of its (nonzero) digits is 27648, while the sum is 34.

The square root of 20686642 is about 4548.2570287969. The cubic root of 20686642 is about 274.5132635266.

The spelling of 20686642 in words is "twenty million, six hundred eighty-six thousand, six hundred forty-two".