21351019 has 4 divisors (see below), whose sum is σ = 21805344. Its totient is φ = 20896696.

The previous prime is 21351017. The next prime is 21351053. The reversal of 21351019 is 91015312.

21351019 = 317² + 318² + ... + 457².

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21351019 - 2¹ = 21351017 is a prime.

It is a super-2 number, since 2×21351019² = 911732024676722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21351013) 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, 227092 + ... + 227185.

It is an arithmetic number, because the mean of its divisors is an integer number (5451336).

Almost surely, 2^21351019 is an apocalyptic number.

21351019 is a deficient number, since it is larger than the sum of its proper divisors (454325).

21351019 is an equidigital number, since it uses as much as digits as its factorization.

21351019 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 454324.

The product of its (nonzero) digits is 270, while the sum is 22.

The square root of 21351019 is about 4620.7162864647. The cubic root of 21351019 is about 277.4211295485.

The spelling of 21351019 in words is "twenty-one million, three hundred fifty-one thousand, nineteen".