20931629 has 2 divisors, whose sum is σ = 20931630. Its totient is φ = 20931628.

The previous prime is 20931623. The next prime is 20931667. The reversal of 20931629 is 92613902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18966025 + 1965604 = 4355^2 + 1402^2 .

It is a cyclic number.

It is not a de Polignac number, because 20931629 - 2⁸ = 20931373 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20931595 and 20931604.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20931623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10465814 + 10465815.

It is an arithmetic number, because the mean of its divisors is an integer number (10465815).

Almost surely, 2^20931629 is an apocalyptic number.

It is an amenable number.

20931629 is a deficient number, since it is larger than the sum of its proper divisors (1).

20931629 is an equidigital number, since it uses as much as digits as its factorization.

20931629 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5832, while the sum is 32.

The square root of 20931629 is about 4575.1097254601. The cubic root of 20931629 is about 275.5926787685.

The spelling of 20931629 in words is "twenty million, nine hundred thirty-one thousand, six hundred twenty-nine".