621866781 has 8 divisors (see below), whose sum is σ = 921284160. Its totient is φ = 414577836.

The previous prime is 621866771. The next prime is 621866813. The reversal of 621866781 is 187668126.

It is a happy number.

621866781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a de Polignac number, because none of the positive numbers 2^k-621866781 is a prime.

It is a super-2 number, since 2×621866781² = 773436586622603922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (621866711) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11516025 + ... + 11516078.

It is an arithmetic number, because the mean of its divisors is an integer number (115160520).

Almost surely, 2^621866781 is an apocalyptic number.

It is an amenable number.

621866781 is a deficient number, since it is larger than the sum of its proper divisors (299417379).

621866781 is a wasteful number, since it uses less digits than its factorization.

621866781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23032112 (or 23032106 counting only the distinct ones).

The product of its digits is 193536, while the sum is 45.

The square root of 621866781 is about 24937.2568860330. The cubic root of 621866781 is about 853.5568514242.

The spelling of 621866781 in words is "six hundred twenty-one million, eight hundred sixty-six thousand, seven hundred eighty-one".