1861990240 has 144 divisors (see below), whose sum is σ = 4990461840. Its totient is φ = 650316800.

The previous prime is 1861990201. The next prime is 1861990241. The reversal of 1861990240 is 420991681.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 1861990193 and 1861990202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1861990241) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9748545 + ... + 9748735.

It is an arithmetic number, because the mean of its divisors is an integer number (34655985).

Almost surely, 2^1861990240 is an apocalyptic number.

1861990240 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 1861990240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2495230920).

1861990240 is an abundant number, since it is smaller than the sum of its proper divisors (3128471600).

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

1861990240 is a wasteful number, since it uses less digits than its factorization.

1861990240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 437 (or 238 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 40.

The square root of 1861990240 is about 43150.7849291296. The cubic root of 1861990240 is about 1230.2474307788.

The spelling of 1861990240 in words is "one billion, eight hundred sixty-one million, nine hundred ninety thousand, two hundred forty".