1987117811 has 16 divisors (see below), whose sum is σ = 2406188736. Its totient is φ = 1601980416.

The previous prime is 1987117807. The next prime is 1987117823. The reversal of 1987117811 is 1187117891.

It is a cyclic number.

It is not a de Polignac number, because 1987117811 - 2² = 1987117807 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1987117801) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 206765 + ... + 216161.

It is an arithmetic number, because the mean of its divisors is an integer number (150386796).

Almost surely, 2^1987117811 is an apocalyptic number.

1987117811 is a deficient number, since it is larger than the sum of its proper divisors (419070925).

1987117811 is a wasteful number, since it uses less digits than its factorization.

1987117811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11198.

The product of its digits is 28224, while the sum is 44.

The square root of 1987117811 is about 44577.0996252560. The cubic root of 1987117811 is about 1257.2101309268.

The spelling of 1987117811 in words is "one billion, nine hundred eighty-seven million, one hundred seventeen thousand, eight hundred eleven".