7621981 has 2 divisors, whose sum is σ = 7621982. Its totient is φ = 7621980.

The previous prime is 7621961. The next prime is 7621997. The reversal of 7621981 is 1891267.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7513081 + 108900 = 2741^2 + 330^2 .

It is a cyclic number.

It is not a de Polignac number, because 7621981 - 2¹⁹ = 7097693 is a prime.

It is a super-2 number, since 2×7621981² = 116189188728722, which contains 22 as substring.

7621981 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7621961) 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, 3810990 + 3810991.

It is an arithmetic number, because the mean of its divisors is an integer number (3810991).

Almost surely, 2^7621981 is an apocalyptic number.

It is an amenable number.

7621981 is a deficient number, since it is larger than the sum of its proper divisors (1).

7621981 is an equidigital number, since it uses as much as digits as its factorization.

7621981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6048, while the sum is 34.

The square root of 7621981 is about 2760.7935453416. The cubic root of 7621981 is about 196.7988791468.

The spelling of 7621981 in words is "seven million, six hundred twenty-one thousand, nine hundred eighty-one".