20678981 has 2 divisors, whose sum is σ = 20678982. Its totient is φ = 20678980.

The previous prime is 20678951. The next prime is 20678993. The reversal of 20678981 is 18987602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10857025 + 9821956 = 3295^2 + 3134^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20678981 is a prime.

It is a super-2 number, since 2×20678981² = 855240510396722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20678921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10339490 + 10339491.

It is an arithmetic number, because the mean of its divisors is an integer number (10339491).

Almost surely, 2^20678981 is an apocalyptic number.

It is an amenable number.

20678981 is a deficient number, since it is larger than the sum of its proper divisors (1).

20678981 is an equidigital number, since it uses as much as digits as its factorization.

20678981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48384, while the sum is 41.

The square root of 20678981 is about 4547.4147600587. The cubic root of 20678981 is about 274.4793719976.

The spelling of 20678981 in words is "twenty million, six hundred seventy-eight thousand, nine hundred eighty-one".