55191811 has 4 divisors (see below), whose sum is σ = 56972224. Its totient is φ = 53411400.

The previous prime is 55191797. The next prime is 55191821. The reversal of 55191811 is 11819155.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 11819155 = 5 ⋅2363831.

It is a cyclic number.

It is not a de Polignac number, because 55191811 - 2¹⁵ = 55159043 is a prime.

It is a super-2 number, since 2×55191811² = 6092272002919442, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (31), and also a Moran number because the ratio is a prime number: 1780381 = 55191811 / (5 + 5 + 1 + 9 + 1 + 8 + 1 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (55191821) 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, 890160 + ... + 890221.

It is an arithmetic number, because the mean of its divisors is an integer number (14243056).

Almost surely, 2^55191811 is an apocalyptic number.

55191811 is a deficient number, since it is larger than the sum of its proper divisors (1780413).

55191811 is a wasteful number, since it uses less digits than its factorization.

55191811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1780412.

The product of its digits is 1800, while the sum is 31.

The square root of 55191811 is about 7429.1191267875. The cubic root of 55191811 is about 380.7368229106.

The spelling of 55191811 in words is "fifty-five million, one hundred ninety-one thousand, eight hundred eleven".