1661511506 has 8 divisors (see below), whose sum is σ = 2623439280. Its totient is φ = 787031748.

The previous prime is 1661511503. The next prime is 1661511521. The reversal of 1661511506 is 6051151661.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1661511503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21861956 + ... + 21862031.

It is an arithmetic number, because the mean of its divisors is an integer number (327929910).

Almost surely, 2^1661511506 is an apocalyptic number.

1661511506 is a deficient number, since it is larger than the sum of its proper divisors (961927774).

1661511506 is a wasteful number, since it uses less digits than its factorization.

1661511506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43724008.

The product of its (nonzero) digits is 5400, while the sum is 32.

The square root of 1661511506 is about 40761.6425822120. The cubic root of 1661511506 is about 1184.4074152043.

The spelling of 1661511506 in words is "one billion, six hundred sixty-one million, five hundred eleven thousand, five hundred six".