1641616621 has 2 divisors, whose sum is σ = 1641616622. Its totient is φ = 1641616620.

The previous prime is 1641616609. The next prime is 1641616643. The reversal of 1641616621 is 1266161461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1584915721 + 56700900 = 39811^2 + 7530^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1641616621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1641616661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 820808310 + 820808311.

It is an arithmetic number, because the mean of its divisors is an integer number (820808311).

Almost surely, 2^1641616621 is an apocalyptic number.

It is an amenable number.

1641616621 is a deficient number, since it is larger than the sum of its proper divisors (1).

1641616621 is an equidigital number, since it uses as much as digits as its factorization.

1641616621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10368, while the sum is 34.

The square root of 1641616621 is about 40516.8683513423. The cubic root of 1641616621 is about 1179.6610682712.

The spelling of 1641616621 in words is "one billion, six hundred forty-one million, six hundred sixteen thousand, six hundred twenty-one".