66999685 has 8 divisors (see below), whose sum is σ = 81916920. Its totient is φ = 52588224.

The previous prime is 66999661. The next prime is 66999689. The reversal of 66999685 is 58699966.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 2502724 + 64496961 = 1582^2 + 8031^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66999685 - 2¹⁵ = 66966917 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66999689) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 126150 + ... + 126679.

It is an arithmetic number, because the mean of its divisors is an integer number (10239615).

Almost surely, 2^66999685 is an apocalyptic number.

It is an amenable number.

66999685 is a deficient number, since it is larger than the sum of its proper divisors (14917235).

66999685 is a wasteful number, since it uses less digits than its factorization.

66999685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 252887.

The product of its digits is 6298560, while the sum is 58.

The square root of 66999685 is about 8185.3335301623. Note that the first 3 decimals coincide. The cubic root of 66999685 is about 406.1541735323.

It can be divided in two parts, 6699 and 9685, that added together give a 14-th power (16384 = 2¹⁴).

The spelling of 66999685 in words is "sixty-six million, nine hundred ninety-nine thousand, six hundred eighty-five".