21016031 has 2 divisors, whose sum is σ = 21016032. Its totient is φ = 21016030.

The previous prime is 21016027. The next prime is 21016049. The reversal of 21016031 is 13061012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21016031 - 2² = 21016027 is a prime.

It is a super-2 number, since 2×21016031² = 883347117985922, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21015997 and 21016015.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21016631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10508015 + 10508016.

It is an arithmetic number, because the mean of its divisors is an integer number (10508016).

Almost surely, 2^21016031 is an apocalyptic number.

21016031 is a deficient number, since it is larger than the sum of its proper divisors (1).

21016031 is an equidigital number, since it uses as much as digits as its factorization.

21016031 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36, while the sum is 14.

The square root of 21016031 is about 4584.3244867701. The cubic root of 21016031 is about 275.9626034538.

Adding to 21016031 its reverse (13061012), we get a palindrome (34077043).

The spelling of 21016031 in words is "twenty-one million, sixteen thousand, thirty-one".