55531021 has 16 divisors (see below), whose sum is σ = 68623744. Its totient is φ = 43758144.

The previous prime is 55531009. The next prime is 55531033. The reversal of 55531021 is 12013555.

It is an interprime number because it is at equal distance from previous prime (55531009) and next prime (55531033).

It is a cyclic number.

It is not a de Polignac number, because 55531021 - 2¹¹ = 55528973 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 55530983 and 55531001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55531001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24106 + ... + 26308.

It is an arithmetic number, because the mean of its divisors is an integer number (4288984).

Almost surely, 2^55531021 is an apocalyptic number.

It is an amenable number.

55531021 is a deficient number, since it is larger than the sum of its proper divisors (13092723).

55531021 is a wasteful number, since it uses less digits than its factorization.

55531021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2500.

The product of its (nonzero) digits is 750, while the sum is 22.

The square root of 55531021 is about 7451.9139152301. The cubic root of 55531021 is about 381.5152358034.

Adding to 55531021 its reverse (12013555), we get a palindrome (67544576).

The spelling of 55531021 in words is "fifty-five million, five hundred thirty-one thousand, twenty-one".