1890340981 has 2 divisors, whose sum is σ = 1890340982. Its totient is φ = 1890340980.

The previous prime is 1890340979. The next prime is 1890341003. The reversal of 1890340981 is 1890430981.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1715202225 + 175138756 = 41415^2 + 13234^2 .

It is a cyclic number.

It is not a de Polignac number, because 1890340981 - 2¹ = 1890340979 is a prime.

It is a super-2 number, since 2×1890340981² = 7146778048896084722, which contains 22 as substring.

Together with 1890340979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1890340961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 945170490 + 945170491.

It is an arithmetic number, because the mean of its divisors is an integer number (945170491).

Almost surely, 2^1890340981 is an apocalyptic number.

It is an amenable number.

1890340981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1890340981 is an equidigital number, since it uses as much as digits as its factorization.

1890340981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 62208, while the sum is 43.

The square root of 1890340981 is about 43478.0517157795. The cubic root of 1890340981 is about 1236.4599389098.

Subtracting 1890340981 from its reverse (1890430981), we obtain a square (90000 = 300²).

The spelling of 1890340981 in words is "one billion, eight hundred ninety million, three hundred forty thousand, nine hundred eighty-one".