1611951221 has 2 divisors, whose sum is σ = 1611951222. Its totient is φ = 1611951220.

The previous prime is 1611951199. The next prime is 1611951223. The reversal of 1611951221 is 1221591161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1572122500 + 39828721 = 39650^2 + 6311^2 .

It is a cyclic number.

It is not a de Polignac number, because 1611951221 - 2¹⁸ = 1611689077 is a prime.

Together with 1611951223, 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 (1611951223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 805975610 + 805975611.

It is an arithmetic number, because the mean of its divisors is an integer number (805975611).

Almost surely, 2^1611951221 is an apocalyptic number.

It is an amenable number.

1611951221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1611951221 is an equidigital number, since it uses as much as digits as its factorization.

1611951221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1080, while the sum is 29.

The square root of 1611951221 is about 40149.1123314078. The cubic root of 1611951221 is about 1172.5120063388.

The spelling of 1611951221 in words is "one billion, six hundred eleven million, nine hundred fifty-one thousand, two hundred twenty-one".