861520 has 60 divisors (see below), whose sum is σ = 2226420. Its totient is φ = 309760.

The previous prime is 861499. The next prime is 861541. The reversal of 861520 is 25168.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (861499) and next prime (861541).

It can be written as a sum of positive squares in 2 ways, for example, as 234256 + 627264 = 484^2 + 792^2 .

It is a Harshad number since it is a multiple of its sum of digits (22).

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 861491 and 861500.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9636 + ... + 9724.

It is an arithmetic number, because the mean of its divisors is an integer number (37107).

2⁸⁶¹⁵²⁰ is an apocalyptic number.

861520 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 861520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1113210).

861520 is an abundant number, since it is smaller than the sum of its proper divisors (1364900).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

861520 is a wasteful number, since it uses less digits than its factorization.

861520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124 (or 107 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 861520 is about 928.1810168281. The cubic root of 861520 is about 95.1528472090.

Adding to 861520 its reverse (25168), we get a palindrome (886688).

The spelling of 861520 in words is "eight hundred sixty-one thousand, five hundred twenty".