1380857561 has 4 divisors (see below), whose sum is σ = 1399773492. Its totient is φ = 1361941632.

The previous prime is 1380857537. The next prime is 1380857587. The reversal of 1380857561 is 1657580831.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1657580831 = 1283 ⋅1291957.

It can be written as a sum of positive squares in 2 ways, for example, as 604176400 + 776681161 = 24580^2 + 27869^2 .

It is a cyclic number.

It is not a de Polignac number, because 1380857561 - 2⁶ = 1380857497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1380857531) 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, 9457856 + ... + 9458001.

It is an arithmetic number, because the mean of its divisors is an integer number (349943373).

Almost surely, 2^1380857561 is an apocalyptic number.

It is an amenable number.

1380857561 is a deficient number, since it is larger than the sum of its proper divisors (18915931).

1380857561 is an equidigital number, since it uses as much as digits as its factorization.

1380857561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18915930.

The product of its (nonzero) digits is 201600, while the sum is 44.

The square root of 1380857561 is about 37159.8918324583. The cubic root of 1380857561 is about 1113.5668506212.

The spelling of 1380857561 in words is "one billion, three hundred eighty million, eight hundred fifty-seven thousand, five hundred sixty-one".