7644671981 has 2 divisors, whose sum is σ = 7644671982. Its totient is φ = 7644671980.

The previous prime is 7644671977. The next prime is 7644672001. The reversal of 7644671981 is 1891764467.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7436302756 + 208369225 = 86234^2 + 14435^2 .

It is a cyclic number.

It is not a de Polignac number, because 7644671981 - 2² = 7644671977 is a prime.

It is a super-2 number, since 2×7644671981² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7644671941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3822335990 + 3822335991.

It is an arithmetic number, because the mean of its divisors is an integer number (3822335991).

Almost surely, 2^7644671981 is an apocalyptic number.

It is an amenable number.

7644671981 is a deficient number, since it is larger than the sum of its proper divisors (1).

7644671981 is an equidigital number, since it uses as much as digits as its factorization.

7644671981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2032128, while the sum is 53.

The square root of 7644671981 is about 87433.8148601558. The cubic root of 7644671981 is about 1969.9397871261.

The spelling of 7644671981 in words is "seven billion, six hundred forty-four million, six hundred seventy-one thousand, nine hundred eighty-one".