661652401 has 2 divisors, whose sum is σ = 661652402. Its totient is φ = 661652400.

The previous prime is 661652399. The next prime is 661652419. The reversal of 661652401 is 104256166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 618815376 + 42837025 = 24876^2 + 6545^2 .

It is a cyclic number.

It is not a de Polignac number, because 661652401 - 2¹ = 661652399 is a prime.

Together with 661652399, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (661652471) 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, 330826200 + 330826201.

It is an arithmetic number, because the mean of its divisors is an integer number (330826201).

Almost surely, 2^661652401 is an apocalyptic number.

It is an amenable number.

661652401 is a deficient number, since it is larger than the sum of its proper divisors (1).

661652401 is an equidigital number, since it uses as much as digits as its factorization.

661652401 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 661652401 is about 25722.6048642046. The cubic root of 661652401 is about 871.3847683323.

The spelling of 661652401 in words is "six hundred sixty-one million, six hundred fifty-two thousand, four hundred one".