21616031 has 2 divisors, whose sum is σ = 21616032. Its totient is φ = 21616030.

The previous prime is 21616019. The next prime is 21616039. The reversal of 21616031 is 13061612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21616031 - 2¹⁴ = 21599647 is a prime.

It is a super-2 number, since 2×21616031² = 934505592385922, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21615994 and 21616012.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21616039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10808015 + 10808016.

It is an arithmetic number, because the mean of its divisors is an integer number (10808016).

Almost surely, 2^21616031 is an apocalyptic number.

21616031 is a deficient number, since it is larger than the sum of its proper divisors (1).

21616031 is an equidigital number, since it uses as much as digits as its factorization.

21616031 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 21616031 is about 4649.3043565678. The cubic root of 21616031 is about 278.5642104889.

Adding to 21616031 its reverse (13061612), we get a palindrome (34677643).

It can be divided in two parts, 2161 and 6031, that added together give a 13-th power (8192 = 2¹³).

The spelling of 21616031 in words is "twenty-one million, six hundred sixteen thousand, thirty-one".