1646755921 has 2 divisors, whose sum is σ = 1646755922. Its totient is φ = 1646755920.

The previous prime is 1646755889. The next prime is 1646755927. The reversal of 1646755921 is 1295576461.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1042579521 + 604176400 = 32289^2 + 24580^2 .

It is a cyclic number.

It is not a de Polignac number, because 1646755921 - 2⁵ = 1646755889 is a prime.

It is not a weakly prime, because it can be changed into another prime (1646755927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 823377960 + 823377961.

It is an arithmetic number, because the mean of its divisors is an integer number (823377961).

Almost surely, 2^1646755921 is an apocalyptic number.

It is an amenable number.

1646755921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1646755921 is an equidigital number, since it uses as much as digits as its factorization.

1646755921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 453600, while the sum is 46.

The square root of 1646755921 is about 40580.2405241763. The cubic root of 1646755921 is about 1180.8908146900.

The spelling of 1646755921 in words is "one billion, six hundred forty-six million, seven hundred fifty-five thousand, nine hundred twenty-one".