1057257781 has 4 divisors (see below), whose sum is σ = 1057558572. Its totient is φ = 1056956992.

The previous prime is 1057257779. The next prime is 1057257787. The reversal of 1057257781 is 1877527501.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1877527501 = 131 ⋅14332271.

It can be written as a sum of positive squares in 2 ways, for example, as 35880100 + 1021377681 = 5990^2 + 31959^2 .

It is a cyclic number.

It is not a de Polignac number, because 1057257781 - 2¹ = 1057257779 is a prime.

It is a super-2 number, since 2×1057257781² = 2235588030970087922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1057257787) 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, 145060 + ... + 152173.

It is an arithmetic number, because the mean of its divisors is an integer number (264389643).

Almost surely, 2^1057257781 is an apocalyptic number.

It is an amenable number.

1057257781 is a deficient number, since it is larger than the sum of its proper divisors (300791).

1057257781 is an equidigital number, since it uses as much as digits as its factorization.

1057257781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 300790.

The product of its (nonzero) digits is 137200, while the sum is 43.

The square root of 1057257781 is about 32515.5006266242. The cubic root of 1057257781 is about 1018.7328173247.

The spelling of 1057257781 in words is "one billion, fifty-seven million, two hundred fifty-seven thousand, seven hundred eighty-one".