621138240 has 448 divisors, whose sum is σ = 2362809600. Its totient is φ = 153280512.

The previous prime is 621138191. The next prime is 621138241. The reversal of 621138240 is 42831126.

621138240 is a `hidden beast` number, since 621 + 1 + 38 + 2 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (621138241) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 9270687 + ... + 9270753.

Almost surely, 2^621138240 is an apocalyptic number.

621138240 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 621138240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1181404800).

621138240 is an abundant number, since it is smaller than the sum of its proper divisors (1741671360).

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

621138240 is a wasteful number, since it uses less digits than its factorization.

621138240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159 (or 143 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 621138240 is about 24922.6451244646. The cubic root of 621138240 is about 853.2233962104.

Adding to 621138240 its reverse (42831126), we get a palindrome (663969366).

The spelling of 621138240 in words is "six hundred twenty-one million, one hundred thirty-eight thousand, two hundred forty".