1819145621 has 2 divisors, whose sum is σ = 1819145622. Its totient is φ = 1819145620.

The previous prime is 1819145579. The next prime is 1819145623. The reversal of 1819145621 is 1265419181.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1782106225 + 37039396 = 42215^2 + 6086^2 .

It is a cyclic number.

It is not a de Polignac number, because 1819145621 - 2¹⁴ = 1819129237 is a prime.

Together with 1819145623, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1819145623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 909572810 + 909572811.

It is an arithmetic number, because the mean of its divisors is an integer number (909572811).

Almost surely, 2^1819145621 is an apocalyptic number.

It is an amenable number.

1819145621 is a deficient number, since it is larger than the sum of its proper divisors (1).

1819145621 is an equidigital number, since it uses as much as digits as its factorization.

1819145621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17280, while the sum is 38.

The square root of 1819145621 is about 42651.4433636190. The cubic root of 1819145621 is about 1220.7380692526.

The spelling of 1819145621 in words is "one billion, eight hundred nineteen million, one hundred forty-five thousand, six hundred twenty-one".