1265858921 has 2 divisors, whose sum is σ = 1265858922. Its totient is φ = 1265858920.

The previous prime is 1265858861. The next prime is 1265858927. The reversal of 1265858921 is 1298585621.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 963481600 + 302377321 = 31040^2 + 17389^2 .

It is an emirp because it is prime and its reverse (1298585621) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1265858921 - 2¹⁰ = 1265857897 is a prime.

It is not a weakly prime, because it can be changed into another prime (1265858927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 632929460 + 632929461.

It is an arithmetic number, because the mean of its divisors is an integer number (632929461).

Almost surely, 2^1265858921 is an apocalyptic number.

It is an amenable number.

1265858921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1265858921 is an equidigital number, since it uses as much as digits as its factorization.

1265858921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 345600, while the sum is 47.

The square root of 1265858921 is about 35578.9111834525. The cubic root of 1265858921 is about 1081.7538150992.

The spelling of 1265858921 in words is "one billion, two hundred sixty-five million, eight hundred fifty-eight thousand, nine hundred twenty-one".