180721381 has 4 divisors (see below), whose sum is σ = 182144512. Its totient is φ = 179298252.

The previous prime is 180721367. The next prime is 180721397. The reversal of 180721381 is 183127081.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 183127081 = 23 ⋅7962047.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-180721381 is a prime.

It is a super-2 number, since 2×180721381² = 65320435101094322, 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 (180724381) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 711375 + ... + 711628.

It is an arithmetic number, because the mean of its divisors is an integer number (45536128).

Almost surely, 2^180721381 is an apocalyptic number.

It is an amenable number.

180721381 is a deficient number, since it is larger than the sum of its proper divisors (1423131).

180721381 is a wasteful number, since it uses less digits than its factorization.

180721381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1423130.

The product of its (nonzero) digits is 2688, while the sum is 31.

The square root of 180721381 is about 13443.2652655521. The cubic root of 180721381 is about 565.3748847307.

The spelling of 180721381 in words is "one hundred eighty million, seven hundred twenty-one thousand, three hundred eighty-one".