672661721 has 2 divisors, whose sum is σ = 672661722. Its totient is φ = 672661720.

The previous prime is 672661673. The next prime is 672661747. The reversal of 672661721 is 127166276.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 374616025 + 298045696 = 19355^2 + 17264^2 .

It is a cyclic number.

It is not a de Polignac number, because 672661721 - 2¹⁰ = 672660697 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (672666721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 336330860 + 336330861.

It is an arithmetic number, because the mean of its divisors is an integer number (336330861).

Almost surely, 2^672661721 is an apocalyptic number.

It is an amenable number.

672661721 is a deficient number, since it is larger than the sum of its proper divisors (1).

672661721 is an equidigital number, since it uses as much as digits as its factorization.

672661721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 42336, while the sum is 38.

The square root of 672661721 is about 25935.7228740592. The cubic root of 672661721 is about 876.1912356238.

The spelling of 672661721 in words is "six hundred seventy-two million, six hundred sixty-one thousand, seven hundred twenty-one".