20640533 has 8 divisors (see below), whose sum is σ = 22081752. Its totient is φ = 19224576.

The previous prime is 20640511. The next prime is 20640541. The reversal of 20640533 is 33504602.

It can be written as a sum of positive squares in 4 ways, for example, as 10252804 + 10387729 = 3202^2 + 3223^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 20640533 - 2⁶ = 20640469 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20640499 and 20640508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20640553) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4610 + ... + 7907.

It is an arithmetic number, because the mean of its divisors is an integer number (2760219).

Almost surely, 2^20640533 is an apocalyptic number.

It is an amenable number.

20640533 is a deficient number, since it is larger than the sum of its proper divisors (1441219).

20640533 is a wasteful number, since it uses less digits than its factorization.

20640533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12631.

The product of its (nonzero) digits is 2160, while the sum is 23.

The square root of 20640533 is about 4543.1853363032. The cubic root of 20640533 is about 274.3091551948.

The spelling of 20640533 in words is "twenty million, six hundred forty thousand, five hundred thirty-three".