55506721 has 8 divisors (see below), whose sum is σ = 55978560. Its totient is φ = 55037328.

The previous prime is 55506713. The next prime is 55506739. The reversal of 55506721 is 12760555.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 55506721 - 2³ = 55506713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (55506761) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 99375 + ... + 99931.

It is an arithmetic number, because the mean of its divisors is an integer number (6997320).

Almost surely, 2^55506721 is an apocalyptic number.

It is an amenable number.

55506721 is a deficient number, since it is larger than the sum of its proper divisors (471839).

55506721 is a wasteful number, since it uses less digits than its factorization.

55506721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1223.

The product of its (nonzero) digits is 10500, while the sum is 31.

The square root of 55506721 is about 7450.2832832047. The cubic root of 55506721 is about 381.4595781867.

The spelling of 55506721 in words is "fifty-five million, five hundred six thousand, seven hundred twenty-one".