66220731 has 24 divisors (see below), whose sum is σ = 98670000. Its totient is φ = 42771456.

The previous prime is 66220727. The next prime is 66220733. The reversal of 66220731 is 13702266.

It is a happy number.

66220731 is a `hidden beast` number, since 6 + 622 + 0 + 7 + 31 = 666.

It is not a de Polignac number, because 66220731 - 2² = 66220727 is a prime.

It is a super-2 number, since 2×66220731² = 8770370428348722, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 66220695 and 66220704.

It is not an unprimeable number, because it can be changed into a prime (66220733) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 52395 + ... + 53643.

It is an arithmetic number, because the mean of its divisors is an integer number (4111250).

Almost surely, 2^66220731 is an apocalyptic number.

66220731 is a deficient number, since it is larger than the sum of its proper divisors (32449269).

66220731 is a wasteful number, since it uses less digits than its factorization.

66220731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1435 (or 1432 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 27.

The square root of 66220731 is about 8137.6121190433. The cubic root of 66220731 is about 404.5740194159.

Adding to 66220731 its reverse (13702266), we get a palindrome (79922997).

The spelling of 66220731 in words is "sixty-six million, two hundred twenty thousand, seven hundred thirty-one".