1661734691 has 4 divisors (see below), whose sum is σ = 1661854512. Its totient is φ = 1661614872.

The previous prime is 1661734673. The next prime is 1661734703. The reversal of 1661734691 is 1964371661.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1661734691 is a prime.

It is a super-2 number, since 2×1661734691² = 5522724366545730962, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1661734631) 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, 35900 + ... + 67913.

It is an arithmetic number, because the mean of its divisors is an integer number (415463628).

Almost surely, 2^1661734691 is an apocalyptic number.

1661734691 is a deficient number, since it is larger than the sum of its proper divisors (119821).

1661734691 is a wasteful number, since it uses less digits than its factorization.

1661734691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 119820.

The product of its digits is 163296, while the sum is 44.

The square root of 1661734691 is about 40764.3801743630. The cubic root of 1661734691 is about 1184.4604452582.

The spelling of 1661734691 in words is "one billion, six hundred sixty-one million, seven hundred thirty-four thousand, six hundred ninety-one".