21026031 has 8 divisors (see below), whose sum is σ = 30191280. Its totient is φ = 12939072.

The previous prime is 21025987. The next prime is 21026053. The reversal of 21026031 is 13062012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21026031 - 2¹⁸ = 20763887 is a prime.

It is a super-2 number, since 2×21026031² = 884187959225922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21026031.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21026081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 269526 + ... + 269603.

It is an arithmetic number, because the mean of its divisors is an integer number (3773910).

Almost surely, 2^21026031 is an apocalyptic number.

21026031 is a deficient number, since it is larger than the sum of its proper divisors (9165249).

21026031 is a wasteful number, since it uses less digits than its factorization.

21026031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 539145.

The product of its (nonzero) digits is 72, while the sum is 15.

The square root of 21026031 is about 4585.4150302890. The cubic root of 21026031 is about 276.0063666878.

Adding to 21026031 its reverse (13062012), we get a palindrome (34088043).

The spelling of 21026031 in words is "twenty-one million, twenty-six thousand, thirty-one".