20671517 has 2 divisors, whose sum is σ = 20671518. Its totient is φ = 20671516.

The previous prime is 20671499. The next prime is 20671529. The reversal of 20671517 is 71517602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18156121 + 2515396 = 4261^2 + 1586^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20671517 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20671517.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20671817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10335758 + 10335759.

It is an arithmetic number, because the mean of its divisors is an integer number (10335759).

Almost surely, 2^20671517 is an apocalyptic number.

It is an amenable number.

20671517 is a deficient number, since it is larger than the sum of its proper divisors (1).

20671517 is an equidigital number, since it uses as much as digits as its factorization.

20671517 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2940, while the sum is 29.

The square root of 20671517 is about 4546.5939999081. The cubic root of 20671517 is about 274.4463439264.

The spelling of 20671517 in words is "twenty million, six hundred seventy-one thousand, five hundred seventeen".