21346421 has 4 divisors (see below), whose sum is σ = 21356844. Its totient is φ = 21336000.

The previous prime is 21346411. The next prime is 21346453. The reversal of 21346421 is 12464312.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 15319396 + 6027025 = 3914^2 + 2455^2 .

It is a cyclic number.

It is not a de Polignac number, because 21346421 - 2⁶ = 21346357 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21346411) 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 in 3 ways as a sum of consecutive naturals, for example, 1010 + ... + 6611.

It is an arithmetic number, because the mean of its divisors is an integer number (5339211).

Almost surely, 2^21346421 is an apocalyptic number.

It is an amenable number.

21346421 is a deficient number, since it is larger than the sum of its proper divisors (10423).

21346421 is an equidigital number, since it uses as much as digits as its factorization.

21346421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10422.

The product of its digits is 1152, while the sum is 23.

The square root of 21346421 is about 4620.2187177665. The cubic root of 21346421 is about 277.4012136539.

The spelling of 21346421 in words is "twenty-one million, three hundred forty-six thousand, four hundred twenty-one".