2646189781 has 2 divisors, whose sum is σ = 2646189782. Its totient is φ = 2646189780.

The previous prime is 2646189743. The next prime is 2646189829. The reversal of 2646189781 is 1879816462.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2533511556 + 112678225 = 50334^2 + 10615^2 .

It is a cyclic number.

It is not a de Polignac number, because 2646189781 - 2⁹ = 2646189269 is a prime.

It is a super-2 number, since 2×2646189781² = 14004640714137655922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2646189701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1323094890 + 1323094891.

It is an arithmetic number, because the mean of its divisors is an integer number (1323094891).

Almost surely, 2^2646189781 is an apocalyptic number.

It is an amenable number.

2646189781 is a deficient number, since it is larger than the sum of its proper divisors (1).

2646189781 is an equidigital number, since it uses as much as digits as its factorization.

2646189781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1161216, while the sum is 52.

The square root of 2646189781 is about 51441.1292741518. The cubic root of 2646189781 is about 1383.1639545976.

The spelling of 2646189781 in words is "two billion, six hundred forty-six million, one hundred eighty-nine thousand, seven hundred eighty-one".