55101821 has 4 divisors (see below), whose sum is σ = 56141532. Its totient is φ = 54062112.

The previous prime is 55101803. The next prime is 55101829. The reversal of 55101821 is 12810155.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12810155 = 5 ⋅2562031.

It can be written as a sum of positive squares in 2 ways, for example, as 49857721 + 5244100 = 7061^2 + 2290^2 .

It is a cyclic number.

It is not a de Polignac number, because 55101821 - 2⁶ = 55101757 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55101829) 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, 519776 + ... + 519881.

It is an arithmetic number, because the mean of its divisors is an integer number (14035383).

Almost surely, 2^55101821 is an apocalyptic number.

It is an amenable number.

55101821 is a deficient number, since it is larger than the sum of its proper divisors (1039711).

55101821 is a wasteful number, since it uses less digits than its factorization.

55101821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1039710.

The product of its (nonzero) digits is 400, while the sum is 23.

The square root of 55101821 is about 7423.0600832810. The cubic root of 55101821 is about 380.5297804491.

Adding to 55101821 its reverse (12810155), we get a palindrome (67911976).

The spelling of 55101821 in words is "fifty-five million, one hundred one thousand, eight hundred twenty-one".