621906660 has 120 divisors (see below), whose sum is σ = 2035889856. Its totient is φ = 158621760.

The previous prime is 621906647. The next prime is 621906661. The reversal of 621906660 is 66609126.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (621906661) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 28915 + ... + 45605.

Almost surely, 2^621906660 is an apocalyptic number.

621906660 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 621906660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1017944928).

621906660 is an abundant number, since it is smaller than the sum of its proper divisors (1413983196).

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

621906660 is a wasteful number, since it uses less digits than its factorization.

621906660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16735 (or 16724 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 36.

The square root of 621906660 is about 24938.0564599569. The cubic root of 621906660 is about 853.5750966320.

It can be divided in two parts, 6219066 and 60, that added together give a palindrome (6219126).

The spelling of 621906660 in words is "six hundred twenty-one million, nine hundred six thousand, six hundred sixty".