55213720 has 64 divisors (see below), whose sum is σ = 130014720. Its totient is φ = 21081984.

The previous prime is 55213703. The next prime is 55213727. The reversal of 55213720 is 2731255.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55213727) 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, 80499 + ... + 81181.

It is an arithmetic number, because the mean of its divisors is an integer number (2031480).

Almost surely, 2^55213720 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 55213720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (65007360).

55213720 is an abundant number, since it is smaller than the sum of its proper divisors (74801000).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

55213720 is a wasteful number, since it uses less digits than its factorization.

55213720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 784 (or 780 counting only the distinct ones).

The product of its (nonzero) digits is 2100, while the sum is 25.

The square root of 55213720 is about 7430.5935159986. The cubic root of 55213720 is about 380.7871954772.

Adding to 55213720 its reverse (2731255), we get a palindrome (57944975).

The spelling of 55213720 in words is "fifty-five million, two hundred thirteen thousand, seven hundred twenty".