51026821 has 4 divisors (see below), whose sum is σ = 51041772. Its totient is φ = 51011872.

The previous prime is 51026813. The next prime is 51026839. The reversal of 51026821 is 12862015.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 30096196 + 20930625 = 5486^2 + 4575^2 .

It is a cyclic number.

It is not a de Polignac number, because 51026821 - 2³ = 51026813 is a prime.

It is a super-2 number, since 2×51026821² = 5207472922732082, 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 (51026891) 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, 435 + ... + 10111.

It is an arithmetic number, because the mean of its divisors is an integer number (12760443).

Almost surely, 2^51026821 is an apocalyptic number.

It is an amenable number.

51026821 is a deficient number, since it is larger than the sum of its proper divisors (14951).

51026821 is an equidigital number, since it uses as much as digits as its factorization.

51026821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14950.

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 51026821 is about 7143.3060273238. The cubic root of 51026821 is about 370.9079745501.

Adding to 51026821 its reverse (12862015), we get a palindrome (63888836).

The spelling of 51026821 in words is "fifty-one million, twenty-six thousand, eight hundred twenty-one".