661201749 has 12 divisors (see below), whose sum is σ = 1028536236. Its totient is φ = 406893312.

The previous prime is 661201727. The next prime is 661201763. The reversal of 661201749 is 947102166.

661201749 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 56927025 + 604274724 = 7545^2 + 24582^2 .

It is not a de Polignac number, because 661201749 - 2¹¹ = 661199701 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661201049) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2825532 + ... + 2825765.

It is an arithmetic number, because the mean of its divisors is an integer number (85711353).

Almost surely, 2^661201749 is an apocalyptic number.

It is an amenable number.

661201749 is a deficient number, since it is larger than the sum of its proper divisors (367334487).

661201749 is a wasteful number, since it uses less digits than its factorization.

661201749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5651316 (or 5651313 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 661201749 is about 25713.8435283409. The cubic root of 661201749 is about 871.1868897705.

It can be divided in two parts, 6612017 and 49, that added together give a triangular number (6612066 = T₃₆₃₆).

The spelling of 661201749 in words is "six hundred sixty-one million, two hundred one thousand, seven hundred forty-nine".