667554721 has 8 divisors (see below), whose sum is σ = 703482080. Its totient is φ = 631706688.

The previous prime is 667554697. The next prime is 667554739. The reversal of 667554721 is 127455766.

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 667554721 - 2⁵ = 667554689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (667554751) 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, 2136 + ... + 36601.

It is an arithmetic number, because the mean of its divisors is an integer number (87935260).

Almost surely, 2^667554721 is an apocalyptic number.

It is an amenable number.

667554721 is a deficient number, since it is larger than the sum of its proper divisors (35927359).

667554721 is a wasteful number, since it uses less digits than its factorization.

667554721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39663.

The product of its digits is 352800, while the sum is 43.

The square root of 667554721 is about 25837.0803497609. The cubic root of 667554721 is about 873.9681860870.

The spelling of 667554721 in words is "six hundred sixty-seven million, five hundred fifty-four thousand, seven hundred twenty-one".