999995621 has 2 divisors, whose sum is σ = 999995622. Its totient is φ = 999995620.

The previous prime is 999995611. The next prime is 999995627. The reversal of 999995621 is 126599999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 704637025 + 295358596 = 26545^2 + 17186^2 .

It is a cyclic number.

It is not a de Polignac number, because 999995621 - 2¹⁴ = 999979237 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999995627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499997810 + 499997811.

It is an arithmetic number, because the mean of its divisors is an integer number (499997811).

Almost surely, 2^999995621 is an apocalyptic number.

It is an amenable number.

999995621 is a deficient number, since it is larger than the sum of its proper divisors (1).

999995621 is an equidigital number, since it uses as much as digits as its factorization.

999995621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3542940, while the sum is 59.

The square root of 999995621 is about 31622.7073635386. The cubic root of 999995621 is about 999.9985403312.

The spelling of 999995621 in words is "nine hundred ninety-nine million, nine hundred ninety-five thousand, six hundred twenty-one".