21379543 has 2 divisors, whose sum is σ = 21379544. Its totient is φ = 21379542.

The previous prime is 21379531. The next prime is 21379549. The reversal of 21379543 is 34597312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21379543 - 2²¹ = 19282391 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21379499 and 21379508.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21379549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10689771 + 10689772.

It is an arithmetic number, because the mean of its divisors is an integer number (10689772).

Almost surely, 2^21379543 is an apocalyptic number.

21379543 is a deficient number, since it is larger than the sum of its proper divisors (1).

21379543 is an equidigital number, since it uses as much as digits as its factorization.

21379543 is an evil number, because the sum of its binary digits is even.

The product of its digits is 22680, while the sum is 34.

The square root of 21379543 is about 4623.8017907345. The cubic root of 21379543 is about 277.5446152869.

The spelling of 21379543 in words is "twenty-one million, three hundred seventy-nine thousand, five hundred forty-three".