1641666631 has 4 divisors (see below), whose sum is σ = 1790909064. Its totient is φ = 1492424200.

The previous prime is 1641666617. The next prime is 1641666647. The reversal of 1641666631 is 1366661461.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1366661461 = 11 ⋅124241951.

It is a cyclic number.

It is not a de Polignac number, because 1641666631 - 2⁷ = 1641666503 is a prime.

It is a super-2 number, since 2×1641666631² = 5390138654677780322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1641666731) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 74621200 + ... + 74621221.

It is an arithmetic number, because the mean of its divisors is an integer number (447727266).

Almost surely, 2^1641666631 is an apocalyptic number.

1641666631 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1641666631 is a deficient number, since it is larger than the sum of its proper divisors (149242433).

1641666631 is a wasteful number, since it uses less digits than its factorization.

1641666631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 149242432.

The product of its digits is 93312, while the sum is 40.

The square root of 1641666631 is about 40517.4854970049. The cubic root of 1641666631 is about 1179.6730471645.

The spelling of 1641666631 in words is "one billion, six hundred forty-one million, six hundred sixty-six thousand, six hundred thirty-one".