661913407 has 2 divisors, whose sum is σ = 661913408. Its totient is φ = 661913406.

The previous prime is 661913359. The next prime is 661913419. The reversal of 661913407 is 704319166.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661913407 - 2¹⁹ = 661389119 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661913467) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330956703 + 330956704.

It is an arithmetic number, because the mean of its divisors is an integer number (330956704).

Almost surely, 2^661913407 is an apocalyptic number.

661913407 is a deficient number, since it is larger than the sum of its proper divisors (1).

661913407 is an equidigital number, since it uses as much as digits as its factorization.

661913407 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27216, while the sum is 37.

The square root of 661913407 is about 25727.6778392454. The cubic root of 661913407 is about 871.4993333984.

The spelling of 661913407 in words is "six hundred sixty-one million, nine hundred thirteen thousand, four hundred seven".