667221765 has 32 divisors (see below), whose sum is σ = 1284280320. Its totient is φ = 288961344.

The previous prime is 667221761. The next prime is 667221769. The reversal of 667221765 is 567122766.

It is an interprime number because it is at equal distance from previous prime (667221761) and next prime (667221769).

It is not a de Polignac number, because 667221765 - 2² = 667221761 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (667221761) 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 31 ways as a sum of consecutive naturals, for example, 165229 + ... + 169218.

It is an arithmetic number, because the mean of its divisors is an integer number (40133760).

Almost surely, 2^667221765 is an apocalyptic number.

It is an amenable number.

667221765 is a deficient number, since it is larger than the sum of its proper divisors (617058555).

667221765 is a wasteful number, since it uses less digits than its factorization.

667221765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 334481.

The product of its digits is 211680, while the sum is 42.

The square root of 667221765 is about 25830.6361710276. The cubic root of 667221765 is about 873.8228590024.

The spelling of 667221765 in words is "six hundred sixty-seven million, two hundred twenty-one thousand, seven hundred sixty-five".