66456981 has 12 divisors (see below), whose sum is σ = 96177900. Its totient is φ = 44219520.

The previous prime is 66456979. The next prime is 66456989. The reversal of 66456981 is 18965466.

66456981 is a `hidden beast` number, since 6 + 6 + 4 + 569 + 81 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 15563025 + 50893956 = 3945^2 + 7134^2 .

It is not a de Polignac number, because 66456981 - 2¹ = 66456979 is a prime.

It is a super-2 number, since 2×66456981² = 8833060647268722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66456989) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1956 + ... + 11693.

It is an arithmetic number, because the mean of its divisors is an integer number (8014825).

Almost surely, 2^66456981 is an apocalyptic number.

It is an amenable number.

66456981 is a deficient number, since it is larger than the sum of its proper divisors (29720919).

66456981 is a wasteful number, since it uses less digits than its factorization.

66456981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14196 (or 14193 counting only the distinct ones).

The product of its digits is 311040, while the sum is 45.

The square root of 66456981 is about 8152.1151243098. The cubic root of 66456981 is about 405.0545696931.

The spelling of 66456981 in words is "sixty-six million, four hundred fifty-six thousand, nine hundred eighty-one".