55721407 has 4 divisors (see below), whose sum is σ = 63681616. Its totient is φ = 47761200.

The previous prime is 55721401. The next prime is 55721417. The reversal of 55721407 is 70412755.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 55721407 - 2³ = 55721399 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55721401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3980094 + ... + 3980107.

It is an arithmetic number, because the mean of its divisors is an integer number (15920404).

Almost surely, 2^55721407 is an apocalyptic number.

55721407 is a deficient number, since it is larger than the sum of its proper divisors (7960209).

55721407 is an equidigital number, since it uses as much as digits as its factorization.

55721407 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7960208.

The product of its (nonzero) digits is 9800, while the sum is 31.

The square root of 55721407 is about 7464.6772870634. The cubic root of 55721407 is about 381.9507419833.

The spelling of 55721407 in words is "fifty-five million, seven hundred twenty-one thousand, four hundred seven".