1921801181 has 2 divisors, whose sum is σ = 1921801182. Its totient is φ = 1921801180.

The previous prime is 1921801177. The next prime is 1921801223. The reversal of 1921801181 is 1811081291.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1615236100 + 306565081 = 40190^2 + 17509^2 .

It is a cyclic number.

It is not a de Polignac number, because 1921801181 - 2² = 1921801177 is a prime.

It is a super-2 number, since 2×1921801181² = 7386639558585989522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1921801171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 960900590 + 960900591.

It is an arithmetic number, because the mean of its divisors is an integer number (960900591).

Almost surely, 2^1921801181 is an apocalyptic number.

It is an amenable number.

1921801181 is a deficient number, since it is larger than the sum of its proper divisors (1).

1921801181 is an equidigital number, since it uses as much as digits as its factorization.

1921801181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 32.

The square root of 1921801181 is about 43838.3528545496. The cubic root of 1921801181 is about 1243.2815398087.

The spelling of 1921801181 in words is "one billion, nine hundred twenty-one million, eight hundred one thousand, one hundred eighty-one".