7651721261 has 2 divisors, whose sum is σ = 7651721262. Its totient is φ = 7651721260.

The previous prime is 7651721257. The next prime is 7651721281. The reversal of 7651721261 is 1621271567.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7442340361 + 209380900 = 86269^2 + 14470^2 .

It is a cyclic number.

It is not a de Polignac number, because 7651721261 - 2² = 7651721257 is a prime.

It is a super-3 number, since 3×7651721261³ (a number of 31 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7651721201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3825860630 + 3825860631.

It is an arithmetic number, because the mean of its divisors is an integer number (3825860631).

Almost surely, 2^7651721261 is an apocalyptic number.

It is an amenable number.

7651721261 is a deficient number, since it is larger than the sum of its proper divisors (1).

7651721261 is an equidigital number, since it uses as much as digits as its factorization.

7651721261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 35280, while the sum is 38.

The square root of 7651721261 is about 87474.1176634552. The cubic root of 7651721261 is about 1970.5451059237.

The spelling of 7651721261 in words is "seven billion, six hundred fifty-one million, seven hundred twenty-one thousand, two hundred sixty-one".