1861216920 has 256 divisors, whose sum is σ = 6513868800. Its totient is φ = 472158720.

The previous prime is 1861216913. The next prime is 1861216921. The reversal of 1861216920 is 296121681.

1861216920 is a `hidden beast` number, since 1 + 8 + 612 + 16 + 9 + 20 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1861216921) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1877625 + ... + 1878615.

It is an arithmetic number, because the mean of its divisors is an integer number (25444800).

Almost surely, 2^1861216920 is an apocalyptic number.

1861216920 is a gapful number since it is divisible by the number (10) 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 1861216920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3256934400).

1861216920 is an abundant number, since it is smaller than the sum of its proper divisors (4652651880).

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

1861216920 is a wasteful number, since it uses less digits than its factorization.

1861216920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1095 (or 1085 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The square root of 1861216920 is about 43141.8233272540. The cubic root of 1861216920 is about 1230.0770921341.

The spelling of 1861216920 in words is "one billion, eight hundred sixty-one million, two hundred sixteen thousand, nine hundred twenty".