55391971 has 4 divisors (see below), whose sum is σ = 55408752. Its totient is φ = 55375192.

The previous prime is 55391969. The next prime is 55391989. The reversal of 55391971 is 17919355.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 17919355 = 5 ⋅3583871.

It is a cyclic number.

It is not a de Polignac number, because 55391971 - 2¹ = 55391969 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (55391951) 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, 1615 + ... + 10648.

It is an arithmetic number, because the mean of its divisors is an integer number (13852188).

Almost surely, 2^55391971 is an apocalyptic number.

55391971 is a deficient number, since it is larger than the sum of its proper divisors (16781).

55391971 is a wasteful number, since it uses less digits than its factorization.

55391971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16780.

The product of its digits is 42525, while the sum is 40.

The square root of 55391971 is about 7442.5782495047. The cubic root of 55391971 is about 381.1965308514.

The spelling of 55391971 in words is "fifty-five million, three hundred ninety-one thousand, nine hundred seventy-one".