1861505361 has 32 divisors (see below), whose sum is σ = 2798784000. Its totient is φ = 1222625664.

The previous prime is 1861505357. The next prime is 1861505377. The reversal of 1861505361 is 1635051681.

1861505361 is a `hidden beast` number, since 1 + 8 + 615 + 0 + 5 + 36 + 1 = 666.

It is not a de Polignac number, because 1861505361 - 2² = 1861505357 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1861505381) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1648245 + ... + 1649373.

It is an arithmetic number, because the mean of its divisors is an integer number (87462000).

Almost surely, 2^1861505361 is an apocalyptic number.

It is an amenable number.

1861505361 is a deficient number, since it is larger than the sum of its proper divisors (937278639).

1861505361 is a wasteful number, since it uses less digits than its factorization.

1861505361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1990 (or 1984 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

The square root of 1861505361 is about 43145.1661371236. The cubic root of 1861505361 is about 1230.1406323437.

It can be divided in two parts, 186150 and 5361, that multiplied together give a triangular number (997950150 = T₄₄₆₇₅).

The spelling of 1861505361 in words is "one billion, eight hundred sixty-one million, five hundred five thousand, three hundred sixty-one".