21642727 has 2 divisors, whose sum is σ = 21642728. Its totient is φ = 21642726.

The previous prime is 21642667. The next prime is 21642749. The reversal of 21642727 is 72724612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21642727 - 2¹¹ = 21640679 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21642757) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10821363 + 10821364.

It is an arithmetic number, because the mean of its divisors is an integer number (10821364).

Almost surely, 2^21642727 is an apocalyptic number.

21642727 is a deficient number, since it is larger than the sum of its proper divisors (1).

21642727 is an equidigital number, since it uses as much as digits as its factorization.

21642727 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9408, while the sum is 31.

The square root of 21642727 is about 4652.1744378301. The cubic root of 21642727 is about 278.6788397789.

The spelling of 21642727 in words is "twenty-one million, six hundred forty-two thousand, seven hundred twenty-seven".