2151561240 has 96 divisors (see below), whose sum is σ = 7021872000. Its totient is φ = 571345920.

The previous prime is 2151561233. The next prime is 2151561241. The reversal of 2151561240 is 421651512.

2151561240 is a `hidden beast` number, since 2 + 1 + 5 + 1 + 5 + 612 + 40 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2151561241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 74361 + ... + 99159.

It is an arithmetic number, because the mean of its divisors is an integer number (73144500).

Almost surely, 2^2151561240 is an apocalyptic number.

2151561240 is a gapful number since it is divisible by the number (20) 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 2151561240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3510936000).

2151561240 is an abundant number, since it is smaller than the sum of its proper divisors (4870310760).

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

2151561240 is a wasteful number, since it uses less digits than its factorization.

2151561240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25057 (or 25050 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 27.

The square root of 2151561240 is about 46384.9247062017. The cubic root of 2151561240 is about 1290.9752135373.

It can be divided in two parts, 2151 and 561240, that added together give a triangular number (563391 = T₁₀₆₁).

The spelling of 2151561240 in words is "two billion, one hundred fifty-one million, five hundred sixty-one thousand, two hundred forty".