661400423 has 2 divisors, whose sum is σ = 661400424. Its totient is φ = 661400422.

The previous prime is 661400401. The next prime is 661400447. The reversal of 661400423 is 324004166.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 661400423 - 2⁶ = 661400359 is a prime.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 661400392 and 661400401.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661400323) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330700211 + 330700212.

It is an arithmetic number, because the mean of its divisors is an integer number (330700212).

Almost surely, 2^661400423 is an apocalyptic number.

661400423 is a deficient number, since it is larger than the sum of its proper divisors (1).

661400423 is an equidigital number, since it uses as much as digits as its factorization.

661400423 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3456, while the sum is 26.

The square root of 661400423 is about 25717.7064101758. The cubic root of 661400423 is about 871.2741373979.

Adding to 661400423 its reverse (324004166), we get a palindrome (985404589).

The spelling of 661400423 in words is "six hundred sixty-one million, four hundred thousand, four hundred twenty-three".