20640618 has 24 divisors (see below), whose sum is σ = 47352708. Its totient is φ = 6475392.

The previous prime is 20640617. The next prime is 20640647. The reversal of 20640618 is 81604602.

20640618 is a `hidden beast` number, since 2 + 0 + 6 + 40 + 618 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 20277009 + 363609 = 4503^2 + 603^2 .

It is a super-2 number, since 2×20640618² = 852070222843848, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20640591 and 20640600.

It is not an unprimeable number, because it can be changed into a prime (20640617) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 33421 + ... + 34032.

Almost surely, 2^20640618 is an apocalyptic number.

20640618 is an abundant number, since it is smaller than the sum of its proper divisors (26712090).

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

20640618 is a wasteful number, since it uses less digits than its factorization.

20640618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67478 (or 67475 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 20640618 is about 4543.1946909636. The cubic root of 20640618 is about 274.3095317394.

The spelling of 20640618 in words is "twenty million, six hundred forty thousand, six hundred eighteen".