621006640 has 60 divisors (see below), whose sum is σ = 1523902464. Its totient is φ = 235317888.

The previous prime is 621006619. The next prime is 621006649. The reversal of 621006640 is 46600126.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (621006649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 18129 + ... + 39631.

Almost surely, 2^621006640 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 621006640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (761951232).

621006640 is an abundant number, since it is smaller than the sum of its proper divisors (902895824).

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

621006640 is a wasteful number, since it uses less digits than its factorization.

621006640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21554 (or 21529 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 621006640 is about 24920.0048154088. The cubic root of 621006640 is about 853.1631347299.

Adding to 621006640 its reverse (46600126), we get a palindrome (667606766).

The spelling of 621006640 in words is "six hundred twenty-one million, six thousand, six hundred forty".