20165557 has 2 divisors, whose sum is σ = 20165558. Its totient is φ = 20165556.

The previous prime is 20165543. The next prime is 20165567. The reversal of 20165557 is 75556102.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19589476 + 576081 = 4426^2 + 759^2 .

It is a cyclic number.

It is not a de Polignac number, because 20165557 - 2⁷ = 20165429 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20165507) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10082778 + 10082779.

It is an arithmetic number, because the mean of its divisors is an integer number (10082779).

Almost surely, 2^20165557 is an apocalyptic number.

It is an amenable number.

20165557 is a deficient number, since it is larger than the sum of its proper divisors (1).

20165557 is an equidigital number, since it uses as much as digits as its factorization.

20165557 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10500, while the sum is 31.

The square root of 20165557 is about 4490.6076426248. The cubic root of 20165557 is about 272.1886891794.

The spelling of 20165557 in words is "twenty million, one hundred sixty-five thousand, five hundred fifty-seven".