1921111820 has 24 divisors (see below), whose sum is σ = 4036419744. Its totient is φ = 768047616.

The previous prime is 1921111789. The next prime is 1921111879. The reversal of 1921111820 is 281111291.

It is a self number, because there is not a number n which added to its sum of digits gives 1921111820.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16529 + ... + 64151.

It is an arithmetic number, because the mean of its divisors is an integer number (168184156).

Almost surely, 2^1921111820 is an apocalyptic number.

1921111820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1921111820 is an abundant number, since it is smaller than the sum of its proper divisors (2115307924).

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

1921111820 is a wasteful number, since it uses less digits than its factorization.

1921111820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49649 (or 49647 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 26.

The square root of 1921111820 is about 43830.4896162477. The cubic root of 1921111820 is about 1243.1328646469.

The spelling of 1921111820 in words is "one billion, nine hundred twenty-one million, one hundred eleven thousand, eight hundred twenty".