66156989 has 2 divisors, whose sum is σ = 66156990. Its totient is φ = 66156988.

The previous prime is 66156983. The next prime is 66157051. The reversal of 66156989 is 98965166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 59552089 + 6604900 = 7717^2 + 2570^2 .

It is a cyclic number.

It is not a de Polignac number, because 66156989 - 2¹² = 66152893 is a prime.

It is a super-2 number, since 2×66156989² = 8753494387092242, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66156983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33078494 + 33078495.

It is an arithmetic number, because the mean of its divisors is an integer number (33078495).

Almost surely, 2^66156989 is an apocalyptic number.

It is an amenable number.

66156989 is a deficient number, since it is larger than the sum of its proper divisors (1).

66156989 is an equidigital number, since it uses as much as digits as its factorization.

66156989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 699840, while the sum is 50.

The square root of 66156989 is about 8133.6946709352. The cubic root of 66156989 is about 404.4441676532. Note that the first 3 decimals are identical.

The spelling of 66156989 in words is "sixty-six million, one hundred fifty-six thousand, nine hundred eighty-nine".