21774421 has 2 divisors, whose sum is σ = 21774422. Its totient is φ = 21774420.

The previous prime is 21774419. The next prime is 21774439. The reversal of 21774421 is 12447712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13793796 + 7980625 = 3714^2 + 2825^2 .

It is a cyclic number.

It is not a de Polignac number, because 21774421 - 2¹ = 21774419 is a prime.

Together with 21774419, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21774421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21774451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10887210 + 10887211.

It is an arithmetic number, because the mean of its divisors is an integer number (10887211).

Almost surely, 2^21774421 is an apocalyptic number.

It is an amenable number.

21774421 is a deficient number, since it is larger than the sum of its proper divisors (1).

21774421 is an equidigital number, since it uses as much as digits as its factorization.

21774421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3136, while the sum is 28.

The square root of 21774421 is about 4666.3069980446. The cubic root of 21774421 is about 279.2429421734.

The spelling of 21774421 in words is "twenty-one million, seven hundred seventy-four thousand, four hundred twenty-one".