624721921 has 2 divisors, whose sum is σ = 624721922. Its totient is φ = 624721920.

The previous prime is 624721907. The next prime is 624721943. The reversal of 624721921 is 129127426.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 611869696 + 12852225 = 24736^2 + 3585^2 .

It is a cyclic number.

It is not a de Polignac number, because 624721921 - 2⁷ = 624721793 is a prime.

It is not a weakly prime, because it can be changed into another prime (624721901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 312360960 + 312360961.

It is an arithmetic number, because the mean of its divisors is an integer number (312360961).

It is a Proth number, since it is equal to 19065 ⋅ 2¹⁵ + 1 and 19065 < 2¹⁵.

Almost surely, 2^624721921 is an apocalyptic number.

It is an amenable number.

624721921 is a deficient number, since it is larger than the sum of its proper divisors (1).

624721921 is an equidigital number, since it uses as much as digits as its factorization.

624721921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12096, while the sum is 34.

The square root of 624721921 is about 24994.4378012389. The cubic root of 624721921 is about 854.8611522875.

The spelling of 624721921 in words is "six hundred twenty-four million, seven hundred twenty-one thousand, nine hundred twenty-one".