623687921 has 2 divisors, whose sum is σ = 623687922. Its totient is φ = 623687920.

The previous prime is 623687917. The next prime is 623687923. The reversal of 623687921 is 129786326.

623687921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 396010000 + 227677921 = 19900^2 + 15089^2 .

It is a cyclic number.

It is not a de Polignac number, because 623687921 - 2² = 623687917 is a prime.

Together with 623687923, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (623687923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 311843960 + 311843961.

It is an arithmetic number, because the mean of its divisors is an integer number (311843961).

Almost surely, 2^623687921 is an apocalyptic number.

It is an amenable number.

623687921 is a deficient number, since it is larger than the sum of its proper divisors (1).

623687921 is an equidigital number, since it uses as much as digits as its factorization.

623687921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 217728, while the sum is 44.

The square root of 623687921 is about 24973.7446331142. The cubic root of 623687921 is about 854.3892545659.

The spelling of 623687921 in words is "six hundred twenty-three million, six hundred eighty-seven thousand, nine hundred twenty-one".