1661631641 has 8 divisors (see below), whose sum is σ = 1715158368. Its totient is φ = 1608724000.

The previous prime is 1661631623. The next prime is 1661631659. The reversal of 1661631641 is 1461361661.

It is an interprime number because it is at equal distance from previous prime (1661631623) and next prime (1661631659).

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

It is a cyclic number.

It is not a de Polignac number, because 1661631641 - 2²² = 1657437337 is a prime.

It is a super-2 number, since 2×1661631641² = 5522039420744705762, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1661631841) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 149315 + ... + 160056.

It is an arithmetic number, because the mean of its divisors is an integer number (214394796).

Almost surely, 2^1661631641 is an apocalyptic number.

It is an amenable number.

1661631641 is a deficient number, since it is larger than the sum of its proper divisors (53526727).

1661631641 is a wasteful number, since it uses less digits than its factorization.

1661631641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 309543.

The product of its digits is 15552, while the sum is 35.

The square root of 1661631641 is about 40763.1161836286. The cubic root of 1661631641 is about 1184.4359605690.

The spelling of 1661631641 in words is "one billion, six hundred sixty-one million, six hundred thirty-one thousand, six hundred forty-one".