20665501 has 2 divisors, whose sum is σ = 20665502. Its totient is φ = 20665500.

The previous prime is 20665493. The next prime is 20665529. The reversal of 20665501 is 10556602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11356900 + 9308601 = 3370^2 + 3051^2 .

It is a cyclic number.

It is not a de Polignac number, because 20665501 - 2³ = 20665493 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20660501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10332750 + 10332751.

It is an arithmetic number, because the mean of its divisors is an integer number (10332751).

Almost surely, 2^20665501 is an apocalyptic number.

It is an amenable number.

20665501 is a deficient number, since it is larger than the sum of its proper divisors (1).

20665501 is an equidigital number, since it uses as much as digits as its factorization.

20665501 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1800, while the sum is 25.

The square root of 20665501 is about 4545.9323576138. The cubic root of 20665501 is about 274.4197174432.

The spelling of 20665501 in words is "twenty million, six hundred sixty-five thousand, five hundred one".