661242401 has 2 divisors, whose sum is σ = 661242402. Its totient is φ = 661242400.

The previous prime is 661242397. The next prime is 661242443. The reversal of 661242401 is 104242166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 547606801 + 113635600 = 23401^2 + 10660^2 .

It is a cyclic number.

It is not a de Polignac number, because 661242401 - 2² = 661242397 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (661242451) 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, 330621200 + 330621201.

It is an arithmetic number, because the mean of its divisors is an integer number (330621201).

Almost surely, 2^661242401 is an apocalyptic number.

It is an amenable number.

661242401 is a deficient number, since it is larger than the sum of its proper divisors (1).

661242401 is an equidigital number, since it uses as much as digits as its factorization.

661242401 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 661242401 is about 25714.6339853399. The cubic root of 661242401 is about 871.2047435061.

Adding to 661242401 its reverse (104242166), we get a palindrome (765484567).

The spelling of 661242401 in words is "six hundred sixty-one million, two hundred forty-two thousand, four hundred one".