21255407 has 2 divisors, whose sum is σ = 21255408. Its totient is φ = 21255406.

The previous prime is 21255401. The next prime is 21255419. The reversal of 21255407 is 70455212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21255407 - 2¹⁰ = 21254383 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21255401) 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, 10627703 + 10627704.

It is an arithmetic number, because the mean of its divisors is an integer number (10627704).

Almost surely, 2^21255407 is an apocalyptic number.

21255407 is a deficient number, since it is larger than the sum of its proper divisors (1).

21255407 is an equidigital number, since it uses as much as digits as its factorization.

21255407 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2800, while the sum is 26.

The square root of 21255407 is about 4610.3586628374. The cubic root of 21255407 is about 277.0064033413.

The spelling of 21255407 in words is "twenty-one million, two hundred fifty-five thousand, four hundred seven".