1561786668 has 72 divisors (see below), whose sum is σ = 4501643328. Its totient is φ = 452279808.

The previous prime is 1561786657. The next prime is 1561786679. The reversal of 1561786668 is 8666871651.

It is an interprime number because it is at equal distance from previous prime (1561786657) and next prime (1561786679).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 90196 + ... + 106107.

It is an arithmetic number, because the mean of its divisors is an integer number (62522824).

Almost surely, 2^1561786668 is an apocalyptic number.

1561786668 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

1561786668 is an abundant number, since it is smaller than the sum of its proper divisors (2939856660).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1561786668 is a wasteful number, since it uses less digits than its factorization.

1561786668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196343 (or 196338 counting only the distinct ones).

The product of its digits is 2903040, while the sum is 54.

The square root of 1561786668 is about 39519.4467066532. The cubic root of 1561786668 is about 1160.2205951855.

The spelling of 1561786668 in words is "one billion, five hundred sixty-one million, seven hundred eighty-six thousand, six hundred sixty-eight".