20640541 has 2 divisors, whose sum is σ = 20640542. Its totient is φ = 20640540.

The previous prime is 20640511. The next prime is 20640553. The reversal of 20640541 is 14504602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18096516 + 2544025 = 4254^2 + 1595^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20640541 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20640511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10320270 + 10320271.

It is an arithmetic number, because the mean of its divisors is an integer number (10320271).

Almost surely, 2^20640541 is an apocalyptic number.

It is an amenable number.

20640541 is a deficient number, since it is larger than the sum of its proper divisors (1).

20640541 is an equidigital number, since it uses as much as digits as its factorization.

20640541 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 960, while the sum is 22.

The square root of 20640541 is about 4543.1862167426. The cubic root of 20640541 is about 274.3091906343.

The spelling of 20640541 in words is "twenty million, six hundred forty thousand, five hundred forty-one".