20640667 has 2 divisors, whose sum is σ = 20640668. Its totient is φ = 20640666.

The previous prime is 20640647. The next prime is 20640679. The reversal of 20640667 is 76604602.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20640667 - 2¹¹ = 20638619 is a prime.

It is not a weakly prime, because it can be changed into another prime (20640617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10320333 + 10320334.

It is an arithmetic number, because the mean of its divisors is an integer number (10320334).

Almost surely, 2^20640667 is an apocalyptic number.

20640667 is a deficient number, since it is larger than the sum of its proper divisors (1).

20640667 is an equidigital number, since it uses as much as digits as its factorization.

20640667 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12096, while the sum is 31.

The square root of 20640667 is about 4543.2000836415. The cubic root of 20640667 is about 274.3097488059.

The spelling of 20640667 in words is "twenty million, six hundred forty thousand, six hundred sixty-seven".