3784689661 has 2 divisors, whose sum is σ = 3784689662. Its totient is φ = 3784689660.

The previous prime is 3784689647. The next prime is 3784689703. The reversal of 3784689661 is 1669864873.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3071265561 + 713424100 = 55419^2 + 26710^2 .

It is a cyclic number.

It is not a de Polignac number, because 3784689661 - 2¹⁹ = 3784165373 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 3784689596 and 3784689605.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3784689611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1892344830 + 1892344831.

It is an arithmetic number, because the mean of its divisors is an integer number (1892344831).

Almost surely, 2^3784689661 is an apocalyptic number.

It is an amenable number.

3784689661 is a deficient number, since it is larger than the sum of its proper divisors (1).

3784689661 is an equidigital number, since it uses as much as digits as its factorization.

3784689661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10450944, while the sum is 58.

The square root of 3784689661 is about 61519.8314448276. The cubic root of 3784689661 is about 1558.3921716569.

It can be divided in two parts, 378468 and 9661, that added together give a square (388129 = 623²).

The spelling of 3784689661 in words is "three billion, seven hundred eighty-four million, six hundred eighty-nine thousand, six hundred sixty-one".