1025781391 has 4 divisors (see below), whose sum is σ = 1027488784. Its totient is φ = 1024074000.

The previous prime is 1025781373. The next prime is 1025781401. The reversal of 1025781391 is 1931875201.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1931875201 = 9181 ⋅210421.

It is a cyclic number.

It is not a de Polignac number, because 1025781391 - 2⁹ = 1025780879 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1025781391.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1025781311) 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, 852795 + ... + 853996.

It is an arithmetic number, because the mean of its divisors is an integer number (256872196).

Almost surely, 2^1025781391 is an apocalyptic number.

1025781391 is a deficient number, since it is larger than the sum of its proper divisors (1707393).

1025781391 is an equidigital number, since it uses as much as digits as its factorization.

1025781391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1707392.

The product of its (nonzero) digits is 15120, while the sum is 37.

The square root of 1025781391 is about 32027.8221395086. The cubic root of 1025781391 is about 1008.5209836102.

The spelling of 1025781391 in words is "one billion, twenty-five million, seven hundred eighty-one thousand, three hundred ninety-one".