651621240 has 128 divisors (see below), whose sum is σ = 2242252800. Its totient is φ = 168151680.

The previous prime is 651621227. The next prime is 651621247. The reversal of 651621240 is 42126156.

651621240 is a `hidden beast` number, since 651 + 6 + 2 + 1 + 2 + 4 + 0 = 666.

It is a super-2 number, since 2×651621240² = 849220480838275200, which contains 22 as substring.

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 (651621247) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 23749 + ... + 43211.

It is an arithmetic number, because the mean of its divisors is an integer number (17517600).

Almost surely, 2^651621240 is an apocalyptic number.

651621240 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 651621240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1121126400).

651621240 is an abundant number, since it is smaller than the sum of its proper divisors (1590631560).

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

651621240 is a wasteful number, since it uses less digits than its factorization.

651621240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19514 (or 19504 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 651621240 is about 25526.8728989667. The cubic root of 651621240 is about 866.9587030293.

Adding to 651621240 its reverse (42126156), we get a palindrome (693747396).

The spelling of 651621240 in words is "six hundred fifty-one million, six hundred twenty-one thousand, two hundred forty".