66106981 has 4 divisors (see below), whose sum is σ = 67190764. Its totient is φ = 65023200.

The previous prime is 66106967. The next prime is 66106987. The reversal of 66106981 is 18960166.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18960166 = 2 ⋅9480083.

It can be written as a sum of positive squares in 2 ways, for example, as 5904900 + 60202081 = 2430^2 + 7759^2 .

It is a cyclic number.

It is not a de Polignac number, because 66106981 - 2¹⁷ = 65975909 is a prime.

It is a super-2 number, since 2×66106981² = 8740265873868722, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66106981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66106987) 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, 541800 + ... + 541921.

It is an arithmetic number, because the mean of its divisors is an integer number (16797691).

Almost surely, 2^66106981 is an apocalyptic number.

66106981 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

66106981 is a deficient number, since it is larger than the sum of its proper divisors (1083783).

66106981 is a wasteful number, since it uses less digits than its factorization.

66106981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1083782.

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 66106981 is about 8130.6199640618. The cubic root of 66106981 is about 404.3422356552.

The spelling of 66106981 in words is "sixty-six million, one hundred six thousand, nine hundred eighty-one".