861611520 has 640 divisors, whose sum is σ = 3620339712. Its totient is φ = 169574400.

The previous prime is 861611477. The next prime is 861611539. The reversal of 861611520 is 25116168.

It is a tau number, because it is divible by the number of its divisors (640).

It is a super-2 number, since 2×861611520² = 1484748822793420800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 18332137 + ... + 18332183.

Almost surely, 2^861611520 is an apocalyptic number.

861611520 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 861611520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1810169856).

861611520 is an abundant number, since it is smaller than the sum of its proper divisors (2758728192).

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

861611520 is a wasteful number, since it uses less digits than its factorization.

861611520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122 (or 106 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 30.

The square root of 861611520 is about 29353.2199255891. The cubic root of 861611520 is about 951.5621647886.

Adding to 861611520 its reverse (25116168), we get a palindrome (886727688).

The spelling of 861611520 in words is "eight hundred sixty-one million, six hundred eleven thousand, five hundred twenty".