1966155421 has 2 divisors, whose sum is σ = 1966155422. Its totient is φ = 1966155420.

The previous prime is 1966155413. The next prime is 1966155449. The reversal of 1966155421 is 1245516691.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1830898521 + 135256900 = 42789^2 + 11630^2 .

It is a cyclic number.

It is not a de Polignac number, because 1966155421 - 2³ = 1966155413 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1966155481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 983077710 + 983077711.

It is an arithmetic number, because the mean of its divisors is an integer number (983077711).

Almost surely, 2^1966155421 is an apocalyptic number.

It is an amenable number.

1966155421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1966155421 is an equidigital number, since it uses as much as digits as its factorization.

1966155421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 64800, while the sum is 40.

The square root of 1966155421 is about 44341.3511408933. The cubic root of 1966155421 is about 1252.7736640248.

The spelling of 1966155421 in words is "one billion, nine hundred sixty-six million, one hundred fifty-five thousand, four hundred twenty-one".