4001621661 has 12 divisors (see below), whose sum is σ = 5792503392. Its totient is φ = 2662032456.

The previous prime is 4001621651. The next prime is 4001621671. The reversal of 4001621661 is 1661261004.

It is an interprime number because it is at equal distance from previous prime (4001621651) and next prime (4001621671).

It is not a de Polignac number, because 4001621661 - 2¹⁷ = 4001490589 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4001621651) 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 11 ways as a sum of consecutive naturals, for example, 471841 + ... + 480246.

It is an arithmetic number, because the mean of its divisors is an integer number (482708616).

Almost surely, 2^4001621661 is an apocalyptic number.

It is an amenable number.

4001621661 is a deficient number, since it is larger than the sum of its proper divisors (1790881731).

4001621661 is a wasteful number, since it uses less digits than its factorization.

4001621661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 952560 (or 952557 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 4001621661 is about 63258.3722601206. The cubic root of 4001621661 is about 1587.6155418498.

Adding to 4001621661 its reverse (1661261004), we get a palindrome (5662882665).

The spelling of 4001621661 in words is "four billion, one million, six hundred twenty-one thousand, six hundred sixty-one".