671991626 has 4 divisors (see below), whose sum is σ = 1007987442. Its totient is φ = 335995812.

The previous prime is 671991613. The next prime is 671991629. The reversal of 671991626 is 626199176.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 372528601 + 299463025 = 19301^2 + 17305^2 .

It is not an unprimeable number, because it can be changed into a prime (671991629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 167997905 + ... + 167997908.

Almost surely, 2^671991626 is an apocalyptic number.

671991626 is a deficient number, since it is larger than the sum of its proper divisors (335995816).

671991626 is a wasteful number, since it uses less digits than its factorization.

671991626 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 335995815.

The product of its digits is 244944, while the sum is 47.

The square root of 671991626 is about 25922.8012760967. The cubic root of 671991626 is about 875.9001896596.

The spelling of 671991626 in words is "six hundred seventy-one million, nine hundred ninety-one thousand, six hundred twenty-six".