861381387 has 24 divisors (see below), whose sum is σ = 1283025744. Its totient is φ = 556605504.

The previous prime is 861381383. The next prime is 861381401. The reversal of 861381387 is 783183168.

It is not a de Polignac number, because 861381387 - 2² = 861381383 is a prime.

It is not an unprimeable number, because it can be changed into a prime (861381383) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 28713 + ... + 50469.

It is an arithmetic number, because the mean of its divisors is an integer number (53459406).

Almost surely, 2^861381387 is an apocalyptic number.

861381387 is a deficient number, since it is larger than the sum of its proper divisors (421644357).

861381387 is a wasteful number, since it uses less digits than its factorization.

861381387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21899 (or 21896 counting only the distinct ones).

The product of its digits is 193536, while the sum is 45.

The square root of 861381387 is about 29349.2995998201. The cubic root of 861381387 is about 951.4774377586.

It can be divided in two parts, 8613 and 81387, that added together give a square (90000 = 300²).

The spelling of 861381387 in words is "eight hundred sixty-one million, three hundred eighty-one thousand, three hundred eighty-seven".