55402121 has 4 divisors (see below), whose sum is σ = 56341200. Its totient is φ = 54463044.

The previous prime is 55402097. The next prime is 55402129. The reversal of 55402121 is 12120455.

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: 12120455 = 5 ⋅2424091.

It is a cyclic number.

It is not a de Polignac number, because 55402121 - 2¹⁰ = 55401097 is a prime.

It is a super-2 number, since 2×55402121² = 6138790022597282, 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 = 55402093 and 55402102.

It is not an unprimeable number, because it can be changed into a prime (55402129) 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, 469451 + ... + 469568.

It is an arithmetic number, because the mean of its divisors is an integer number (14085300).

Almost surely, 2^55402121 is an apocalyptic number.

It is an amenable number.

55402121 is a deficient number, since it is larger than the sum of its proper divisors (939079).

55402121 is an equidigital number, since it uses as much as digits as its factorization.

55402121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 939078.

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

The square root of 55402121 is about 7443.2601056258. The cubic root of 55402121 is about 381.2198128567.

Adding to 55402121 its reverse (12120455), we get a palindrome (67522576).

The spelling of 55402121 in words is "fifty-five million, four hundred two thousand, one hundred twenty-one".