55778221 has 4 divisors (see below), whose sum is σ = 55900732. Its totient is φ = 55655712.

The previous prime is 55778119. The next prime is 55778231. The reversal of 55778221 is 12287755.

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 23629321 + 32148900 = 4861^2 + 5670^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55778221 is a prime.

It is a super-2 number, since 2×55778221² = 6222419875849682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55778231) 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, 60570 + ... + 61483.

It is an arithmetic number, because the mean of its divisors is an integer number (13975183).

Almost surely, 2^55778221 is an apocalyptic number.

It is an amenable number.

55778221 is a deficient number, since it is larger than the sum of its proper divisors (122511).

55778221 is a wasteful number, since it uses less digits than its factorization.

55778221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 122510.

The product of its digits is 39200, while the sum is 37.

The square root of 55778221 is about 7468.4818403743. The cubic root of 55778221 is about 382.0805112502.

The spelling of 55778221 in words is "fifty-five million, seven hundred seventy-eight thousand, two hundred twenty-one".