1565260991 has 4 divisors (see below), whose sum is σ = 1788869712. Its totient is φ = 1341652272.

The previous prime is 1565260969. The next prime is 1565261003. The reversal of 1565260991 is 1990625651.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1565260991 - 2¹⁸ = 1564998847 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1565260591) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111804350 + ... + 111804363.

It is an arithmetic number, because the mean of its divisors is an integer number (447217428).

Almost surely, 2^1565260991 is an apocalyptic number.

1565260991 is a deficient number, since it is larger than the sum of its proper divisors (223608721).

1565260991 is an equidigital number, since it uses as much as digits as its factorization.

1565260991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 223608720.

The product of its (nonzero) digits is 145800, while the sum is 44.

The square root of 1565260991 is about 39563.3794183460. The cubic root of 1565260991 is about 1161.0802934159.

The spelling of 1565260991 in words is "one billion, five hundred sixty-five million, two hundred sixty thousand, nine hundred ninety-one".