1891381555 has 16 divisors (see below), whose sum is σ = 2636420544. Its totient is φ = 1275684480.

The previous prime is 1891381523. The next prime is 1891381571. The reversal of 1891381555 is 5551831981.

It is not a de Polignac number, because 1891381555 - 2⁵ = 1891381523 is a prime.

It is a Duffinian 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, 440812 + ... + 445081.

It is an arithmetic number, because the mean of its divisors is an integer number (164776284).

Almost surely, 2^1891381555 is an apocalyptic number.

1891381555 is a deficient number, since it is larger than the sum of its proper divisors (745038989).

1891381555 is an equidigital number, since it uses as much as digits as its factorization.

1891381555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 885966.

The product of its digits is 216000, while the sum is 46.

The square root of 1891381555 is about 43490.0167279802. The cubic root of 1891381555 is about 1236.6867748910.

The spelling of 1891381555 in words is "one billion, eight hundred ninety-one million, three hundred eighty-one thousand, five hundred fifty-five".