1388281561 has 4 divisors (see below), whose sum is σ = 1388360500. Its totient is φ = 1388202624.

The previous prime is 1388281553. The next prime is 1388281571. The reversal of 1388281561 is 1651828831.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1651828831 = 31 ⋅53284801.

It can be written as a sum of positive squares in 2 ways, for example, as 181413961 + 1206867600 = 13469^2 + 34740^2 .

It is a cyclic number.

It is not a de Polignac number, because 1388281561 - 2³ = 1388281553 is a prime.

It is a super-2 number, since 2×1388281561² = 3854651385225193442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1388281571) 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, 205 + ... + 52693.

It is an arithmetic number, because the mean of its divisors is an integer number (347090125).

Almost surely, 2^1388281561 is an apocalyptic number.

It is an amenable number.

1388281561 is a deficient number, since it is larger than the sum of its proper divisors (78939).

1388281561 is an equidigital number, since it uses as much as digits as its factorization.

1388281561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78938.

The product of its digits is 92160, while the sum is 43.

The square root of 1388281561 is about 37259.6505753878. The cubic root of 1388281561 is about 1115.5589336402.

The spelling of 1388281561 in words is "one billion, three hundred eighty-eight million, two hundred eighty-one thousand, five hundred sixty-one".