20166557 has 2 divisors, whose sum is σ = 20166558. Its totient is φ = 20166556.

The previous prime is 20166551. The next prime is 20166583. The reversal of 20166557 is 75566102.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19061956 + 1104601 = 4366^2 + 1051^2 .

It is a cyclic number.

It is not a de Polignac number, because 20166557 - 2⁴ = 20166541 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20166551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10083278 + 10083279.

It is an arithmetic number, because the mean of its divisors is an integer number (10083279).

Almost surely, 2^20166557 is an apocalyptic number.

It is an amenable number.

20166557 is a deficient number, since it is larger than the sum of its proper divisors (1).

20166557 is an equidigital number, since it uses as much as digits as its factorization.

20166557 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12600, while the sum is 32.

The square root of 20166557 is about 4490.7189847507. The cubic root of 20166557 is about 272.1931883392.

The spelling of 20166557 in words is "twenty million, one hundred sixty-six thousand, five hundred fifty-seven".