1955216621 has 2 divisors, whose sum is σ = 1955216622. Its totient is φ = 1955216620.

The previous prime is 1955216617. The next prime is 1955216677. The reversal of 1955216621 is 1266125591.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1932042025 + 23174596 = 43955^2 + 4814^2 .

It is a cyclic number.

It is not a de Polignac number, because 1955216621 - 2² = 1955216617 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1955212621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 977608310 + 977608311.

It is an arithmetic number, because the mean of its divisors is an integer number (977608311).

Almost surely, 2^1955216621 is an apocalyptic number.

It is an amenable number.

1955216621 is a deficient number, since it is larger than the sum of its proper divisors (1).

1955216621 is an equidigital number, since it uses as much as digits as its factorization.

1955216621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32400, while the sum is 38.

The square root of 1955216621 is about 44217.8314823330. The cubic root of 1955216621 is about 1250.4460532902.

The spelling of 1955216621 in words is "one billion, nine hundred fifty-five million, two hundred sixteen thousand, six hundred twenty-one".