667422721 has 16 divisors (see below), whose sum is σ = 776817664. Its totient is φ = 561613824.

The previous prime is 667422673. The next prime is 667422739. The reversal of 667422721 is 127224766.

It is a cyclic number.

It is not a de Polignac number, because 667422721 - 2¹⁹ = 666898433 is a prime.

It is not an unprimeable number, because it can be changed into a prime (667482721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 111025 + ... + 116881.

It is an arithmetic number, because the mean of its divisors is an integer number (48551104).

Almost surely, 2^667422721 is an apocalyptic number.

It is an amenable number.

667422721 is a deficient number, since it is larger than the sum of its proper divisors (109394943).

667422721 is a wasteful number, since it uses less digits than its factorization.

667422721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6160.

The product of its digits is 56448, while the sum is 37.

The square root of 667422721 is about 25834.5257552756. The cubic root of 667422721 is about 873.9105771242.

The spelling of 667422721 in words is "six hundred sixty-seven million, four hundred twenty-two thousand, seven hundred twenty-one".