55181721 has 8 divisors (see below), whose sum is σ = 84086464. Its totient is φ = 31532400.

The previous prime is 55181701. The next prime is 55181723. The reversal of 55181721 is 12718155.

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

It is not a de Polignac number, because 55181721 - 2¹⁵ = 55148953 is a prime.

It is not an unprimeable number, because it can be changed into a prime (55181723) 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, 1313830 + ... + 1313871.

It is an arithmetic number, because the mean of its divisors is an integer number (10510808).

Almost surely, 2^55181721 is an apocalyptic number.

It is an amenable number.

55181721 is a deficient number, since it is larger than the sum of its proper divisors (28904743).

55181721 is a wasteful number, since it uses less digits than its factorization.

55181721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2627711.

The product of its digits is 2800, while the sum is 30.

The square root of 55181721 is about 7428.4400112002. The cubic root of 55181721 is about 380.7136197783.

Adding to 55181721 its reverse (12718155), we get a palindrome (67899876).

The spelling of 55181721 in words is "fifty-five million, one hundred eighty-one thousand, seven hundred twenty-one".