21210019 has 4 divisors (see below), whose sum is σ = 21661344. Its totient is φ = 20758696.

The previous prime is 21210011. The next prime is 21210037. The reversal of 21210019 is 91001212.

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 21210019 - 2³ = 21210011 is a prime.

It is a super-2 number, since 2×21210019² = 899729811960722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21209984 and 21210011.

It is not an unprimeable number, because it can be changed into a prime (21210011) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 225592 + ... + 225685.

It is an arithmetic number, because the mean of its divisors is an integer number (5415336).

Almost surely, 2^21210019 is an apocalyptic number.

21210019 is a deficient number, since it is larger than the sum of its proper divisors (451325).

21210019 is an equidigital number, since it uses as much as digits as its factorization.

21210019 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 451324.

The product of its (nonzero) digits is 36, while the sum is 16.

The square root of 21210019 is about 4605.4336386490. The cubic root of 21210019 is about 276.8090931321.

The spelling of 21210019 in words is "twenty-one million, two hundred ten thousand, nineteen".