21926381 has 2 divisors, whose sum is σ = 21926382. Its totient is φ = 21926380.

The previous prime is 21926369. The next prime is 21926419. The reversal of 21926381 is 18362912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21855625 + 70756 = 4675^2 + 266^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21926381 is a prime.

It is a super-2 number, since 2×21926381² = 961532367514322, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21926321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10963190 + 10963191.

It is an arithmetic number, because the mean of its divisors is an integer number (10963191).

Almost surely, 2^21926381 is an apocalyptic number.

It is an amenable number.

21926381 is a deficient number, since it is larger than the sum of its proper divisors (1).

21926381 is an equidigital number, since it uses as much as digits as its factorization.

21926381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5184, while the sum is 32.

The square root of 21926381 is about 4682.5613717281. The cubic root of 21926381 is about 279.8910332795.

The spelling of 21926381 in words is "twenty-one million, nine hundred twenty-six thousand, three hundred eighty-one".