651261440 has 80 divisors (see below), whose sum is σ = 1585224432. Its totient is φ = 256548864.

The previous prime is 651261431. The next prime is 651261451. The reversal of 651261440 is 44162156.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 169622 + ... + 173418.

Almost surely, 2^651261440 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 651261440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (792612216).

651261440 is an abundant number, since it is smaller than the sum of its proper divisors (933962992).

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

651261440 is an equidigital number, since it uses as much as digits as its factorization.

651261440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3887 (or 3871 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 29.

The square root of 651261440 is about 25519.8244508069. The cubic root of 651261440 is about 866.7991066503.

It can be divided in two parts, 65126 and 1440, that added together give a palindrome (66566).

The spelling of 651261440 in words is "six hundred fifty-one million, two hundred sixty-one thousand, four hundred forty".