21420215 has 8 divisors (see below), whose sum is σ = 26189568. Its totient is φ = 16812640.

The previous prime is 21420209. The next prime is 21420227. The reversal of 21420215 is 51202412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21420215 - 2¹⁴ = 21403831 is a prime.

It is a super-2 number, since 2×21420215² = 917651221292450, 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 = 21420193 and 21420202.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40151 + ... + 40680.

It is an arithmetic number, because the mean of its divisors is an integer number (3273696).

Almost surely, 2^21420215 is an apocalyptic number.

21420215 is a deficient number, since it is larger than the sum of its proper divisors (4769353).

21420215 is an equidigital number, since it uses as much as digits as its factorization.

21420215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80889.

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21420215 is about 4628.1978134043. The cubic root of 21420215 is about 277.7205021762.

Adding to 21420215 its reverse (51202412), we get a palindrome (72622627).

The spelling of 21420215 in words is "twenty-one million, four hundred twenty thousand, two hundred fifteen".