626664021 has 4 divisors (see below), whose sum is σ = 835552032. Its totient is φ = 417776012.

The previous prime is 626663959. The next prime is 626664029. The reversal of 626664021 is 120466626.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 626664021 - 2⁹ = 626663509 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (626664029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 104444001 + ... + 104444006.

It is an arithmetic number, because the mean of its divisors is an integer number (208888008).

Almost surely, 2^626664021 is an apocalyptic number.

It is an amenable number.

626664021 is a deficient number, since it is larger than the sum of its proper divisors (208888011).

626664021 is a wasteful number, since it uses less digits than its factorization.

626664021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 208888010.

The product of its (nonzero) digits is 20736, while the sum is 33.

The square root of 626664021 is about 25033.2582977127. The cubic root of 626664021 is about 855.7460838322.

The spelling of 626664021 in words is "six hundred twenty-six million, six hundred sixty-four thousand, twenty-one".