66213261 has 8 divisors (see below), whose sum is σ = 98093760. Its totient is φ = 44142156.

The previous prime is 66213253. The next prime is 66213299. The reversal of 66213261 is 16231266.

66213261 is a `hidden beast` number, since 6 + 621 + 32 + 6 + 1 = 666.

It is not a de Polignac number, because 66213261 - 2³ = 66213253 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 2452343 = 66213261 / (6 + 6 + 2 + 1 + 3 + 2 + 6 + 1).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66213211) 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, 1226145 + ... + 1226198.

It is an arithmetic number, because the mean of its divisors is an integer number (12261720).

Almost surely, 2^66213261 is an apocalyptic number.

It is an amenable number.

66213261 is a deficient number, since it is larger than the sum of its proper divisors (31880499).

66213261 is a wasteful number, since it uses less digits than its factorization.

66213261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2452352 (or 2452346 counting only the distinct ones).

The product of its digits is 2592, while the sum is 27.

The square root of 66213261 is about 8137.1531262475. The cubic root of 66213261 is about 404.5588062466.

The spelling of 66213261 in words is "sixty-six million, two hundred thirteen thousand, two hundred sixty-one".