55802821 has 4 divisors (see below), whose sum is σ = 57602944. Its totient is φ = 54002700.

The previous prime is 55802797. The next prime is 55802833. The reversal of 55802821 is 12820855.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12820855 = 5 ⋅2564171.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55802821 is a prime.

It is a super-2 number, since 2×55802821² = 6227909663116082, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (31), and also a Moran number because the ratio is a prime number: 1800091 = 55802821 / (5 + 5 + 8 + 0 + 2 + 8 + 2 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55802321) 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, 900015 + ... + 900076.

It is an arithmetic number, because the mean of its divisors is an integer number (14400736).

Almost surely, 2^55802821 is an apocalyptic number.

It is an amenable number.

55802821 is a deficient number, since it is larger than the sum of its proper divisors (1800123).

55802821 is a wasteful number, since it uses less digits than its factorization.

55802821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1800122.

The product of its (nonzero) digits is 6400, while the sum is 31.

The square root of 55802821 is about 7470.1285798840. The cubic root of 55802821 is about 382.1366729502.

The spelling of 55802821 in words is "fifty-five million, eight hundred two thousand, eight hundred twenty-one".