7391251981 has 2 divisors, whose sum is σ = 7391251982. Its totient is φ = 7391251980.

The previous prime is 7391251957. The next prime is 7391251991. The reversal of 7391251981 is 1891521937.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5466236356 + 1925015625 = 73934^2 + 43875^2 .

It is a cyclic number.

It is not a de Polignac number, because 7391251981 - 2⁵ = 7391251949 is a prime.

It is a super-2 number, since 2×7391251981² (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 (7391251991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3695625990 + 3695625991.

It is an arithmetic number, because the mean of its divisors is an integer number (3695625991).

Almost surely, 2^7391251981 is an apocalyptic number.

It is an amenable number.

7391251981 is a deficient number, since it is larger than the sum of its proper divisors (1).

7391251981 is an equidigital number, since it uses as much as digits as its factorization.

7391251981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 136080, while the sum is 46.

The square root of 7391251981 is about 85972.3908065839. The cubic root of 7391251981 is about 1947.9269646879.

The spelling of 7391251981 in words is "seven billion, three hundred ninety-one million, two hundred fifty-one thousand, nine hundred eighty-one".