621666620 has 48 divisors (see below), whose sum is σ = 1359318240. Its totient is φ = 238527744.

The previous prime is 621666611. The next prime is 621666623. The reversal of 621666620 is 26666126.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (621666623) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 87647 + ... + 94473.

It is an arithmetic number, because the mean of its divisors is an integer number (28319130).

Almost surely, 2^621666620 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 621666620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (679659120).

621666620 is an abundant number, since it is smaller than the sum of its proper divisors (737651620).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

621666620 is a wasteful number, since it uses less digits than its factorization.

621666620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7022 (or 7020 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 35.

The square root of 621666620 is about 24933.2432707821. The cubic root of 621666620 is about 853.4652631441.

It can be divided in two parts, 62166 and 6620, that added together give a palindrome (68786).

The spelling of 621666620 in words is "six hundred twenty-one million, six hundred sixty-six thousand, six hundred twenty".