1205402661 has 16 divisors (see below), whose sum is σ = 1847361600. Its totient is φ = 775890864.

The previous prime is 1205402659. The next prime is 1205402677. The reversal of 1205402661 is 1662045021.

It is not a de Polignac number, because 1205402661 - 2¹ = 1205402659 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1205402621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 768951 + ... + 770516.

It is an arithmetic number, because the mean of its divisors is an integer number (115460100).

Almost surely, 2^1205402661 is an apocalyptic number.

It is an amenable number.

1205402661 is a deficient number, since it is larger than the sum of its proper divisors (641958939).

1205402661 is a wasteful number, since it uses less digits than its factorization.

1205402661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1539505 (or 1539499 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 1205402661 is about 34718.9092714619. The cubic root of 1205402661 is about 1064.2509551478.

Adding to 1205402661 its reverse (1662045021), we get a palindrome (2867447682).

It can be divided in two parts, 120540 and 2661, that added together give a square (123201 = 351²).

The spelling of 1205402661 in words is "one billion, two hundred five million, four hundred two thousand, six hundred sixty-one".