55120421 has 4 divisors (see below), whose sum is σ = 55135500. Its totient is φ = 55105344.

The previous prime is 55120399. The next prime is 55120423. The reversal of 55120421 is 12402155.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 9084196 + 46036225 = 3014^2 + 6785^2 .

It is a cyclic number.

It is not a de Polignac number, because 55120421 - 2¹⁸ = 54858277 is a prime.

It is a super-2 number, since 2×55120421² = 6076521622434482, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 55120393 and 55120402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55120423) 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, 1805 + ... + 10653.

It is an arithmetic number, because the mean of its divisors is an integer number (13783875).

Almost surely, 2^55120421 is an apocalyptic number.

It is an amenable number.

55120421 is a deficient number, since it is larger than the sum of its proper divisors (15079).

55120421 is an equidigital number, since it uses as much as digits as its factorization.

55120421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15078.

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 55120421 is about 7424.3128301547. The cubic root of 55120421 is about 380.5725924503.

Adding to 55120421 its reverse (12402155), we get a palindrome (67522576).

The spelling of 55120421 in words is "fifty-five million, one hundred twenty thousand, four hundred twenty-one".