621728991 has 24 divisors (see below), whose sum is σ = 978017040. Its totient is φ = 378297216.

The previous prime is 621728983. The next prime is 621729029. The reversal of 621728991 is 199827126.

It is not a de Polignac number, because 621728991 - 2³ = 621728983 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (621728951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 19441 + ... + 40266.

It is an arithmetic number, because the mean of its divisors is an integer number (40750710).

Almost surely, 2^621728991 is an apocalyptic number.

621728991 is a deficient number, since it is larger than the sum of its proper divisors (356288049).

621728991 is a wasteful number, since it uses less digits than its factorization.

621728991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59815 (or 59812 counting only the distinct ones).

The product of its digits is 108864, while the sum is 45.

The square root of 621728991 is about 24934.4939992774. The cubic root of 621728991 is about 853.4938045413.

The spelling of 621728991 in words is "six hundred twenty-one million, seven hundred twenty-eight thousand, nine hundred ninety-one".