21408727 has 2 divisors, whose sum is σ = 21408728. Its totient is φ = 21408726.

The previous prime is 21408721. The next prime is 21408733. The reversal of 21408727 is 72780412.

It is a balanced prime because it is at equal distance from previous prime (21408721) and next prime (21408733).

It is a cyclic number.

It is not a de Polignac number, because 21408727 - 2³ = 21408719 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21408721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10704363 + 10704364.

It is an arithmetic number, because the mean of its divisors is an integer number (10704364).

Almost surely, 2^21408727 is an apocalyptic number.

21408727 is a deficient number, since it is larger than the sum of its proper divisors (1).

21408727 is an equidigital number, since it uses as much as digits as its factorization.

21408727 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6272, while the sum is 31.

The square root of 21408727 is about 4626.9565591218. The cubic root of 21408727 is about 277.6708446656.

Subtracting from 21408727 its sum of digits (31), we obtain a triangular number (21408696 = T₆₅₄₃).

The spelling of 21408727 in words is "twenty-one million, four hundred eight thousand, seven hundred twenty-seven".