861988 has 6 divisors (see below), whose sum is σ = 1508486. Its totient is φ = 430992.

The previous prime is 861979. The next prime is 861997. The reversal of 861988 is 889168.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (861979) and next prime (861997).

It can be written as a sum of positive squares in only one way, i.e., 719104 + 142884 = 848^2 + 378^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 861988.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107745 + ... + 107752.

2⁸⁶¹⁹⁸⁸ is an apocalyptic number.

It is an amenable number.

861988 is a deficient number, since it is larger than the sum of its proper divisors (646498).

861988 is a wasteful number, since it uses less digits than its factorization.

861988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 215501 (or 215499 counting only the distinct ones).

The product of its digits is 27648, while the sum is 40.

The square root of 861988 is about 928.4330885960. The cubic root of 861988 is about 95.1700739212.

It can be divided in two parts, 861 and 988, that added together give a square (1849 = 43²).

The spelling of 861988 in words is "eight hundred sixty-one thousand, nine hundred eighty-eight".