2190239981 has 2 divisors, whose sum is σ = 2190239982. Its totient is φ = 2190239980.

The previous prime is 2190239977. The next prime is 2190240037. The reversal of 2190239981 is 1899320912.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2164575625 + 25664356 = 46525^2 + 5066^2 .

It is a cyclic number.

It is not a de Polignac number, because 2190239981 - 2² = 2190239977 is a prime.

It is a super-2 number, since 2×2190239981² = 9594302348741760722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2190239911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1095119990 + 1095119991.

It is an arithmetic number, because the mean of its divisors is an integer number (1095119991).

Almost surely, 2^2190239981 is an apocalyptic number.

It is an amenable number.

2190239981 is a deficient number, since it is larger than the sum of its proper divisors (1).

2190239981 is an equidigital number, since it uses as much as digits as its factorization.

2190239981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 69984, while the sum is 44.

The square root of 2190239981 is about 46799.9997970085. Note that the first 3 decimals coincide. The cubic root of 2190239981 is about 1298.6652930476.

The spelling of 2190239981 in words is "two billion, one hundred ninety million, two hundred thirty-nine thousand, nine hundred eighty-one".