4000213661 has 2 divisors, whose sum is σ = 4000213662. Its totient is φ = 4000213660.

The previous prime is 4000213649. The next prime is 4000213691. The reversal of 4000213661 is 1663120004.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3541440100 + 458773561 = 59510^2 + 21419^2 .

It is a cyclic number.

It is not a de Polignac number, because 4000213661 - 2¹⁴ = 4000197277 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (4000213691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2000106830 + 2000106831.

It is an arithmetic number, because the mean of its divisors is an integer number (2000106831).

Almost surely, 2^4000213661 is an apocalyptic number.

It is an amenable number.

4000213661 is a deficient number, since it is larger than the sum of its proper divisors (1).

4000213661 is an equidigital number, since it uses as much as digits as its factorization.

4000213661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 4000213661 is about 63247.2423193296. The cubic root of 4000213661 is about 1587.4293152730.

Adding to 4000213661 its reverse (1663120004), we get a palindrome (5663333665).

The spelling of 4000213661 in words is "four billion, two hundred thirteen thousand, six hundred sixty-one".