166036781 has 4 divisors (see below), whose sum is σ = 166089792. Its totient is φ = 165983772.

The previous prime is 166036771. The next prime is 166036789. The reversal of 166036781 is 187630661.

166036781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 187630661 = 619 ⋅303119.

It is a cyclic number.

It is not a de Polignac number, because 166036781 - 2¹⁴ = 166020397 is a prime.

It is a super-2 number, since 2×166036781² = 55136425289683922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166036789) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21491 + ... + 28176.

It is an arithmetic number, because the mean of its divisors is an integer number (41522448).

Almost surely, 2^166036781 is an apocalyptic number.

It is an amenable number.

166036781 is a deficient number, since it is larger than the sum of its proper divisors (53011).

166036781 is an equidigital number, since it uses as much as digits as its factorization.

166036781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53010.

The product of its (nonzero) digits is 36288, while the sum is 38.

The square root of 166036781 is about 12885.5260272912. The cubic root of 166036781 is about 549.6270540557.

The spelling of 166036781 in words is "one hundred sixty-six million, thirty-six thousand, seven hundred eighty-one".