21761543 has 2 divisors, whose sum is σ = 21761544. Its totient is φ = 21761542.

The previous prime is 21761539. The next prime is 21761617. The reversal of 21761543 is 34516712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21761543 - 2² = 21761539 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21761743) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10880771 + 10880772.

It is an arithmetic number, because the mean of its divisors is an integer number (10880772).

Almost surely, 2^21761543 is an apocalyptic number.

21761543 is a deficient number, since it is larger than the sum of its proper divisors (1).

21761543 is an equidigital number, since it uses as much as digits as its factorization.

21761543 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5040, while the sum is 29.

The square root of 21761543 is about 4664.9269018925. The cubic root of 21761543 is about 279.1878806284.

The spelling of 21761543 in words is "twenty-one million, seven hundred sixty-one thousand, five hundred forty-three".