1905401221 has 2 divisors, whose sum is σ = 1905401222. Its totient is φ = 1905401220.

The previous prime is 1905401219. The next prime is 1905401231. The reversal of 1905401221 is 1221045091.

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., 1442936196 + 462465025 = 37986^2 + 21505^2 .

It is a cyclic number.

It is not a de Polignac number, because 1905401221 - 2¹ = 1905401219 is a prime.

Together with 1905401219, 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 (1905401231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 952700610 + 952700611.

It is an arithmetic number, because the mean of its divisors is an integer number (952700611).

Almost surely, 2^1905401221 is an apocalyptic number.

It is an amenable number.

1905401221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1905401221 is an equidigital number, since it uses as much as digits as its factorization.

1905401221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 1905401221 is about 43650.9017203540. The cubic root of 1905401221 is about 1239.7348594139.

The spelling of 1905401221 in words is "one billion, nine hundred five million, four hundred one thousand, two hundred twenty-one".