21547741 has 2 divisors, whose sum is σ = 21547742. Its totient is φ = 21547740.

The previous prime is 21547717. The next prime is 21547751. The reversal of 21547741 is 14774512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21483225 + 64516 = 4635^2 + 254^2 .

It is a cyclic number.

It is not a de Polignac number, because 21547741 - 2⁷ = 21547613 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21547751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10773870 + 10773871.

It is an arithmetic number, because the mean of its divisors is an integer number (10773871).

Almost surely, 2^21547741 is an apocalyptic number.

It is an amenable number.

21547741 is a deficient number, since it is larger than the sum of its proper divisors (1).

21547741 is an equidigital number, since it uses as much as digits as its factorization.

21547741 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7840, while the sum is 31.

The square root of 21547741 is about 4641.9544375187. The cubic root of 21547741 is about 278.2705516145.

The spelling of 21547741 in words is "twenty-one million, five hundred forty-seven thousand, seven hundred forty-one".