2154891581 has 8 divisors (see below), whose sum is σ = 2232721464. Its totient is φ = 2078092800.

The previous prime is 2154891577. The next prime is 2154891589. The reversal of 2154891581 is 1851984512.

It can be written as a sum of positive squares in 4 ways, for example, as 61371556 + 2093520025 = 7834^2 + 45755^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2154891581 - 2² = 2154891577 is a prime.

It is a super-2 number, since 2×2154891581² = 9287115451729359122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2154891589) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 253520 + ... + 261881.

It is an arithmetic number, because the mean of its divisors is an integer number (279090183).

Almost surely, 2^2154891581 is an apocalyptic number.

It is an amenable number.

2154891581 is a deficient number, since it is larger than the sum of its proper divisors (77829883).

2154891581 is a wasteful number, since it uses less digits than its factorization.

2154891581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 515551.

The product of its digits is 115200, while the sum is 44.

The square root of 2154891581 is about 46420.8097839751. The cubic root of 2154891581 is about 1291.6409582082.

The spelling of 2154891581 in words is "two billion, one hundred fifty-four million, eight hundred ninety-one thousand, five hundred eighty-one".