166738639 has 2 divisors, whose sum is σ = 166738640. Its totient is φ = 166738638.

The previous prime is 166738631. The next prime is 166738673. The reversal of 166738639 is 936837661.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 166738639 - 2³ = 166738631 is a prime.

It is a super-3 number, since 3×166738639³ (a number of 26 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 166738592 and 166738601.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166738631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83369319 + 83369320.

It is an arithmetic number, because the mean of its divisors is an integer number (83369320).

Almost surely, 2^166738639 is an apocalyptic number.

166738639 is a deficient number, since it is larger than the sum of its proper divisors (1).

166738639 is an equidigital number, since it uses as much as digits as its factorization.

166738639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 979776, while the sum is 49.

The square root of 166738639 is about 12912.7316629751. The cubic root of 166738639 is about 550.4004125520.

The spelling of 166738639 in words is "one hundred sixty-six million, seven hundred thirty-eight thousand, six hundred thirty-nine".