661465621 has 2 divisors, whose sum is σ = 661465622. Its totient is φ = 661465620.

The previous prime is 661465583. The next prime is 661465771. The reversal of 661465621 is 126564166.

661465621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 571879396 + 89586225 = 23914^2 + 9465^2 .

It is a cyclic number.

It is not a de Polignac number, because 661465621 - 2¹³ = 661457429 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661460621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330732810 + 330732811.

It is an arithmetic number, because the mean of its divisors is an integer number (330732811).

Almost surely, 2^661465621 is an apocalyptic number.

It is an amenable number.

661465621 is a deficient number, since it is larger than the sum of its proper divisors (1).

661465621 is an equidigital number, since it uses as much as digits as its factorization.

661465621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51840, while the sum is 37.

The square root of 661465621 is about 25718.9739492072. The cubic root of 661465621 is about 871.3027652723.

The spelling of 661465621 in words is "six hundred sixty-one million, four hundred sixty-five thousand, six hundred twenty-one".