21678793 has 2 divisors, whose sum is σ = 21678794. Its totient is φ = 21678792.

The previous prime is 21678779. The next prime is 21678799. The reversal of 21678793 is 39787612.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19254544 + 2424249 = 4388^2 + 1557^2 .

It is a cyclic number.

It is not a de Polignac number, because 21678793 - 2¹³ = 21670601 is a prime.

It is not a weakly prime, because it can be changed into another prime (21678799) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10839396 + 10839397.

It is an arithmetic number, because the mean of its divisors is an integer number (10839397).

Almost surely, 2^21678793 is an apocalyptic number.

It is an amenable number.

21678793 is a deficient number, since it is larger than the sum of its proper divisors (1).

21678793 is an equidigital number, since it uses as much as digits as its factorization.

21678793 is an evil number, because the sum of its binary digits is even.

The product of its digits is 127008, while the sum is 43.

The square root of 21678793 is about 4656.0490762018. The cubic root of 21678793 is about 278.8335530799.

The spelling of 21678793 in words is "twenty-one million, six hundred seventy-eight thousand, seven hundred ninety-three".