181964921 has 4 divisors (see below), whose sum is σ = 182083200. Its totient is φ = 181846644.

The previous prime is 181964899. The next prime is 181964941. The reversal of 181964921 is 129469181.

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: 129469181 = 887 ⋅145963.

It is a cyclic number.

It is not a de Polignac number, because 181964921 - 2¹⁰ = 181963897 is a prime.

It is a super-2 number, since 2×181964921² = 66222464949072482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (181964941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 56801 + ... + 59918.

It is an arithmetic number, because the mean of its divisors is an integer number (45520800).

Almost surely, 2^181964921 is an apocalyptic number.

It is an amenable number.

181964921 is a deficient number, since it is larger than the sum of its proper divisors (118279).

181964921 is a wasteful number, since it uses less digits than its factorization.

181964921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118278.

The product of its digits is 31104, while the sum is 41.

The square root of 181964921 is about 13489.4373863405. The cubic root of 181964921 is about 566.6686992238.

The spelling of 181964921 in words is "one hundred eighty-one million, nine hundred sixty-four thousand, nine hundred twenty-one".