3781955621 has 2 divisors, whose sum is σ = 3781955622. Its totient is φ = 3781955620.

The previous prime is 3781955591. The next prime is 3781955623. The reversal of 3781955621 is 1265591873.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3491628100 + 290327521 = 59090^2 + 17039^2 .

It is a cyclic number.

It is not a de Polignac number, because 3781955621 - 2¹⁸ = 3781693477 is a prime.

Together with 3781955623, 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 (3781955623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1890977810 + 1890977811.

It is an arithmetic number, because the mean of its divisors is an integer number (1890977811).

Almost surely, 2^3781955621 is an apocalyptic number.

It is an amenable number.

3781955621 is a deficient number, since it is larger than the sum of its proper divisors (1).

3781955621 is an equidigital number, since it uses as much as digits as its factorization.

3781955621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 453600, while the sum is 47.

The square root of 3781955621 is about 61497.6066282258. The cubic root of 3781955621 is about 1558.0168231433.

The spelling of 3781955621 in words is "three billion, seven hundred eighty-one million, nine hundred fifty-five thousand, six hundred twenty-one".