1641954991 has 2 divisors, whose sum is σ = 1641954992. Its totient is φ = 1641954990.

The previous prime is 1641954967. The next prime is 1641955093. The reversal of 1641954991 is 1994591461.

It is a weak prime.

It is an emirp because it is prime and its reverse (1994591461) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1641954991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1641954791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 820977495 + 820977496.

It is an arithmetic number, because the mean of its divisors is an integer number (820977496).

Almost surely, 2^1641954991 is an apocalyptic number.

1641954991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1641954991 is an equidigital number, since it uses as much as digits as its factorization.

1641954991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 349920, while the sum is 49.

The square root of 1641954991 is about 40521.0438044234. The cubic root of 1641954991 is about 1179.7421132786.

The spelling of 1641954991 in words is "one billion, six hundred forty-one million, nine hundred fifty-four thousand, nine hundred ninety-one".