21729611 has 2 divisors, whose sum is σ = 21729612. Its totient is φ = 21729610.

The previous prime is 21729583. The next prime is 21729637. The reversal of 21729611 is 11692712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21729611 - 2¹⁴ = 21713227 is a prime.

It is a super-2 number, since 2×21729611² = 944351988422642, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21729511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10864805 + 10864806.

It is an arithmetic number, because the mean of its divisors is an integer number (10864806).

Almost surely, 2^21729611 is an apocalyptic number.

21729611 is a deficient number, since it is larger than the sum of its proper divisors (1).

21729611 is an equidigital number, since it uses as much as digits as its factorization.

21729611 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1512, while the sum is 29.

The square root of 21729611 is about 4661.5030837703. The cubic root of 21729611 is about 279.0512574812.

The spelling of 21729611 in words is "twenty-one million, seven hundred twenty-nine thousand, six hundred eleven".