55551021 has 4 divisors (see below), whose sum is σ = 74068032. Its totient is φ = 37034012.

The previous prime is 55551017. The next prime is 55551043. The reversal of 55551021 is 12015555.

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.

It is a cyclic number.

It is not a de Polignac number, because 55551021 - 2² = 55551017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 55550982 and 55551000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55551011) 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, 9258501 + ... + 9258506.

It is an arithmetic number, because the mean of its divisors is an integer number (18517008).

Almost surely, 2^55551021 is an apocalyptic number.

It is an amenable number.

55551021 is a deficient number, since it is larger than the sum of its proper divisors (18517011).

55551021 is a wasteful number, since it uses less digits than its factorization.

55551021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18517010.

The product of its (nonzero) digits is 1250, while the sum is 24.

The square root of 55551021 is about 7453.2557315579. The cubic root of 55551021 is about 381.5610323613.

Adding to 55551021 its reverse (12015555), we get a palindrome (67566576).

The spelling of 55551021 in words is "fifty-five million, five hundred fifty-one thousand, twenty-one".