3999223621 has 2 divisors, whose sum is σ = 3999223622. Its totient is φ = 3999223620.

The previous prime is 3999223619. The next prime is 3999223639. The reversal of 3999223621 is 1263229993.

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., 2744292996 + 1254930625 = 52386^2 + 35425^2 .

It is a cyclic number.

It is not a de Polignac number, because 3999223621 - 2¹ = 3999223619 is a prime.

Together with 3999223619, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3999293621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1999611810 + 1999611811.

It is an arithmetic number, because the mean of its divisors is an integer number (1999611811).

Almost surely, 2^3999223621 is an apocalyptic number.

It is an amenable number.

3999223621 is a deficient number, since it is larger than the sum of its proper divisors (1).

3999223621 is an equidigital number, since it uses as much as digits as its factorization.

3999223621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 314928, while the sum is 46.

The square root of 3999223621 is about 63239.4150905905. The cubic root of 3999223621 is about 1587.2983432527.

The spelling of 3999223621 in words is "three billion, nine hundred ninety-nine million, two hundred twenty-three thousand, six hundred twenty-one".