20386640 has 20 divisors (see below), whose sum is σ = 47399124. Its totient is φ = 8154624.

The previous prime is 20386631. The next prime is 20386651. The reversal of 20386640 is 4668302.

It can be written as a sum of positive squares in 2 ways, for example, as 12138256 + 8248384 = 3484^2 + 2872^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 127337 + ... + 127496.

Almost surely, 2^20386640 is an apocalyptic number.

20386640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20386640 is an abundant number, since it is smaller than the sum of its proper divisors (27012484).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20386640 is a wasteful number, since it uses less digits than its factorization.

20386640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 254846 (or 254840 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 29.

The square root of 20386640 is about 4515.1566971701. The cubic root of 20386640 is about 273.1797802347.

The spelling of 20386640 in words is "twenty million, three hundred eighty-six thousand, six hundred forty".