861669900 has 540 divisors, whose sum is σ = 3520118448. Its totient is φ = 180714240.

The previous prime is 861669869. The next prime is 861669943. The reversal of 861669900 is 9966168.

It is a tau number, because it is divible by the number of its divisors (540).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 179 ways as a sum of consecutive naturals, for example, 5159617 + ... + 5159783.

Almost surely, 2^861669900 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 861669900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1760059224).

861669900 is an abundant number, since it is smaller than the sum of its proper divisors (2658448548).

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

861669900 is a wasteful number, since it uses less digits than its factorization.

861669900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220 (or 197 counting only the distinct ones).

The product of its (nonzero) digits is 139968, while the sum is 45.

The square root of 861669900 is about 29354.2143481988. The cubic root of 861669900 is about 951.5836558911.

It can be divided in two parts, 861 and 669900, that added together give a square (670761 = 819²).

The spelling of 861669900 in words is "eight hundred sixty-one million, six hundred sixty-nine thousand, nine hundred".