20681951 has 2 divisors, whose sum is σ = 20681952. Its totient is φ = 20681950.

The previous prime is 20681939. The next prime is 20681953. The reversal of 20681951 is 15918602.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20681951 - 2¹⁰ = 20680927 is a prime.

Together with 20681953, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20681953) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10340975 + 10340976.

It is an arithmetic number, because the mean of its divisors is an integer number (10340976).

Almost surely, 2^20681951 is an apocalyptic number.

20681951 is a deficient number, since it is larger than the sum of its proper divisors (1).

20681951 is an equidigital number, since it uses as much as digits as its factorization.

20681951 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 32.

The square root of 20681951 is about 4547.7413075064. The cubic root of 20681951 is about 274.4925119860.

The spelling of 20681951 in words is "twenty million, six hundred eighty-one thousand, nine hundred fifty-one".