620919991 has 2 divisors, whose sum is σ = 620919992. Its totient is φ = 620919990.

The previous prime is 620919911. The next prime is 620919997. The reversal of 620919991 is 199919026.

620919991 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 is a cyclic number.

It is not a de Polignac number, because 620919991 - 2⁹ = 620919479 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (620919997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 310459995 + 310459996.

It is an arithmetic number, because the mean of its divisors is an integer number (310459996).

Almost surely, 2^620919991 is an apocalyptic number.

620919991 is a deficient number, since it is larger than the sum of its proper divisors (1).

620919991 is an equidigital number, since it uses as much as digits as its factorization.

620919991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 78732, while the sum is 46.

The square root of 620919991 is about 24918.2662117572. The cubic root of 620919991 is about 853.1234522927.

The spelling of 620919991 in words is "six hundred twenty million, nine hundred nineteen thousand, nine hundred ninety-one".