1981211700 has 144 divisors (see below), whose sum is σ = 6498403520. Its totient is φ = 461998080.

The previous prime is 1981211693. The next prime is 1981211737. The reversal of 1981211700 is 71121891.

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 47 ways as a sum of consecutive naturals, for example, 60732 + ... + 87468.

Almost surely, 2^1981211700 is an apocalyptic number.

1981211700 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 1981211700, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3249201760).

1981211700 is an abundant number, since it is smaller than the sum of its proper divisors (4517191820).

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

1981211700 is a wasteful number, since it uses less digits than its factorization.

1981211700 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26786 (or 26779 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 30.

The square root of 1981211700 is about 44510.8043063704. The cubic root of 1981211700 is about 1255.9633350015.

The spelling of 1981211700 in words is "one billion, nine hundred eighty-one million, two hundred eleven thousand, seven hundred".