21028837 has 2 divisors, whose sum is σ = 21028838. Its totient is φ = 21028836.

The previous prime is 21028823. The next prime is 21028853. The reversal of 21028837 is 73882012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19945156 + 1083681 = 4466^2 + 1041^2 .

It is a cyclic number.

It is not a de Polignac number, because 21028837 - 2¹⁵ = 20996069 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21028799 and 21028808.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21028897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10514418 + 10514419.

It is an arithmetic number, because the mean of its divisors is an integer number (10514419).

Almost surely, 2^21028837 is an apocalyptic number.

It is an amenable number.

21028837 is a deficient number, since it is larger than the sum of its proper divisors (1).

21028837 is an equidigital number, since it uses as much as digits as its factorization.

21028837 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5376, while the sum is 31.

The square root of 21028837 is about 4585.7209902043. The cubic root of 21028837 is about 276.0186441582.

The spelling of 21028837 in words is "twenty-one million, twenty-eight thousand, eight hundred thirty-seven".