1781133421 has 2 divisors, whose sum is σ = 1781133422. Its totient is φ = 1781133420.

The previous prime is 1781133407. The next prime is 1781133467. The reversal of 1781133421 is 1243311871.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 996349225 + 784784196 = 31565^2 + 28014^2 .

It is an emirp because it is prime and its reverse (1243311871) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1781133421 - 2¹⁵ = 1781100653 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1781133821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 890566710 + 890566711.

It is an arithmetic number, because the mean of its divisors is an integer number (890566711).

Almost surely, 2^1781133421 is an apocalyptic number.

It is an amenable number.

1781133421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1781133421 is an equidigital number, since it uses as much as digits as its factorization.

1781133421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4032, while the sum is 31.

The square root of 1781133421 is about 42203.4764089405. The cubic root of 1781133421 is about 1212.1754505432.

The spelling of 1781133421 in words is "one billion, seven hundred eighty-one million, one hundred thirty-three thousand, four hundred twenty-one".