661378423 has 2 divisors, whose sum is σ = 661378424. Its totient is φ = 661378422.

The previous prime is 661378381. The next prime is 661378439. The reversal of 661378423 is 324873166.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661378423 - 2¹³ = 661370231 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661378453) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330689211 + 330689212.

It is an arithmetic number, because the mean of its divisors is an integer number (330689212).

Almost surely, 2^661378423 is an apocalyptic number.

661378423 is a deficient number, since it is larger than the sum of its proper divisors (1).

661378423 is an equidigital number, since it uses as much as digits as its factorization.

661378423 is an evil number, because the sum of its binary digits is even.

The product of its digits is 145152, while the sum is 40.

The square root of 661378423 is about 25717.2786857397. The cubic root of 661378423 is about 871.2644769648.

The spelling of 661378423 in words is "six hundred sixty-one million, three hundred seventy-eight thousand, four hundred twenty-three".