21742447 has 2 divisors, whose sum is σ = 21742448. Its totient is φ = 21742446.

The previous prime is 21742411. The next prime is 21742451. The reversal of 21742447 is 74424712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21742447 - 2⁷ = 21742319 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21749447) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10871223 + 10871224.

It is an arithmetic number, because the mean of its divisors is an integer number (10871224).

Almost surely, 2^21742447 is an apocalyptic number.

21742447 is a deficient number, since it is larger than the sum of its proper divisors (1).

21742447 is an equidigital number, since it uses as much as digits as its factorization.

21742447 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12544, while the sum is 31.

The square root of 21742447 is about 4662.8796896339. The cubic root of 21742447 is about 279.1061932227.

The spelling of 21742447 in words is "twenty-one million, seven hundred forty-two thousand, four hundred forty-seven".