55531209 has 4 divisors (see below), whose sum is σ = 74041616. Its totient is φ = 37020804.

The previous prime is 55531207. The next prime is 55531211. The reversal of 55531209 is 90213555.

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 an interprime number because it is at equal distance from previous prime (55531207) and next prime (55531211).

It is not a de Polignac number, because 55531209 - 2¹ = 55531207 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (55531207) 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, 9255199 + ... + 9255204.

It is an arithmetic number, because the mean of its divisors is an integer number (18510404).

Almost surely, 2^55531209 is an apocalyptic number.

It is an amenable number.

55531209 is a deficient number, since it is larger than the sum of its proper divisors (18510407).

55531209 is a wasteful number, since it uses less digits than its factorization.

55531209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18510406.

The product of its (nonzero) digits is 6750, while the sum is 30.

The square root of 55531209 is about 7451.9265294285. The cubic root of 55531209 is about 381.5156663422.

The spelling of 55531209 in words is "fifty-five million, five hundred thirty-one thousand, two hundred nine".