1861161638 has 32 divisors (see below), whose sum is σ = 3226169088. Its totient is φ = 788767200.

The previous prime is 1861161619. The next prime is 1861161677. The reversal of 1861161638 is 8361611681.

It is a junction number, because it is equal to n+sod(n) for n = 1861161595 and 1861161604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1588793 + ... + 1589963.

It is an arithmetic number, because the mean of its divisors is an integer number (100817784).

Almost surely, 2^1861161638 is an apocalyptic number.

1861161638 is a deficient number, since it is larger than the sum of its proper divisors (1365007450).

1861161638 is a wasteful number, since it uses less digits than its factorization.

1861161638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2348.

The product of its digits is 41472, while the sum is 41.

The square root of 1861161638 is about 43141.1826217131. The cubic root of 1861161638 is about 1230.0649134005.

The spelling of 1861161638 in words is "one billion, eight hundred sixty-one million, one hundred sixty-one thousand, six hundred thirty-eight".