1525561661 has 32 divisors (see below), whose sum is σ = 1782816000. Its totient is φ = 1293304320.

The previous prime is 1525561651. The next prime is 1525561669. The reversal of 1525561661 is 1661655251.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1525561661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1525561669) 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 in 31 ways as a sum of consecutive naturals, for example, 2014895 + ... + 2015651.

It is an arithmetic number, because the mean of its divisors is an integer number (55713000).

Almost surely, 2^1525561661 is an apocalyptic number.

It is an amenable number.

1525561661 is a deficient number, since it is larger than the sum of its proper divisors (257254339).

1525561661 is a wasteful number, since it uses less digits than its factorization.

1525561661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1029.

The product of its digits is 54000, while the sum is 38.

The square root of 1525561661 is about 39058.4390497111. The cubic root of 1525561661 is about 1151.1800517091.

The spelling of 1525561661 in words is "one billion, five hundred twenty-five million, five hundred sixty-one thousand, six hundred sixty-one".