20172989 has 2 divisors, whose sum is σ = 20172990. Its totient is φ = 20172988.

The previous prime is 20172979. The next prime is 20173051. The reversal of 20172989 is 98927102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16467364 + 3705625 = 4058^2 + 1925^2 .

It is a cyclic number.

It is not a de Polignac number, because 20172989 - 2⁴ = 20172973 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20172949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10086494 + 10086495.

It is an arithmetic number, because the mean of its divisors is an integer number (10086495).

Almost surely, 2^20172989 is an apocalyptic number.

It is an amenable number.

20172989 is a deficient number, since it is larger than the sum of its proper divisors (1).

20172989 is an equidigital number, since it uses as much as digits as its factorization.

20172989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 20172989 is about 4491.4350713330. The cubic root of 20172989 is about 272.2221233807. Note that the first 3 decimals are identical.

The spelling of 20172989 in words is "twenty million, one hundred seventy-two thousand, nine hundred eighty-nine".