55221540 has 96 divisors (see below), whose sum is σ = 174182400. Its totient is φ = 12950400.

The previous prime is 55221533. The next prime is 55221541. The reversal of 55221540 is 4512255.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 55221540.

It is not an unprimeable number, because it can be changed into a prime (55221541) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 19111 + ... + 21809.

It is an arithmetic number, because the mean of its divisors is an integer number (1814400).

Almost surely, 2^55221540 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 55221540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (87091200).

55221540 is an abundant number, since it is smaller than the sum of its proper divisors (118960860).

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

55221540 is a wasteful number, since it uses less digits than its factorization.

55221540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2753 (or 2751 counting only the distinct ones).

The product of its (nonzero) digits is 2000, while the sum is 24.

The square root of 55221540 is about 7431.1197002874. The cubic root of 55221540 is about 380.8051717779.

Adding to 55221540 its reverse (4512255), we get a palindrome (59733795).

It can be divided in two parts, 552215 and 40, that added together give a palindrome (552255).

The spelling of 55221540 in words is "fifty-five million, two hundred twenty-one thousand, five hundred forty".