55155251021 has 4 divisors (see below), whose sum is σ = 59397962652. Its totient is φ = 50912539392.

The previous prime is 55155250981. The next prime is 55155251029. The reversal of 55155251021 is 12015255155.

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

It can be written as a sum of positive squares in 2 ways, for example, as 9408030025 + 45747220996 = 96995^2 + 213886^2 .

It is a de Polignac number, because none of the positive numbers 2^k-55155251021 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 (55155251029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2121355796 + ... + 2121355821.

It is an arithmetic number, because the mean of its divisors is an integer number (14849490663).

Almost surely, 2^55155251021 is an apocalyptic number.

It is an amenable number.

55155251021 is a deficient number, since it is larger than the sum of its proper divisors (4242711631).

55155251021 is a wasteful number, since it uses less digits than its factorization.

55155251021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4242711630.

The product of its (nonzero) digits is 12500, while the sum is 32.

The spelling of 55155251021 in words is "fifty-five billion, one hundred fifty-five million, two hundred fifty-one thousand, twenty-one".