21420115 has 4 divisors (see below), whose sum is σ = 25704144. Its totient is φ = 17136088.

The previous prime is 21420103. The next prime is 21420121. The reversal of 21420115 is 51102412.

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 21420115 - 2¹⁵ = 21387347 is a prime.

It is a super-2 number, since 2×21420115² = 917642653226450, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2142007 + ... + 2142016.

It is an arithmetic number, because the mean of its divisors is an integer number (6426036).

Almost surely, 2^21420115 is an apocalyptic number.

21420115 is a deficient number, since it is larger than the sum of its proper divisors (4284029).

21420115 is an equidigital number, since it uses as much as digits as its factorization.

21420115 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4284028.

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 21420115 is about 4628.1870100505. The cubic root of 21420115 is about 277.7200699973.

Adding to 21420115 its reverse (51102412), we get a palindrome (72522527).

The spelling of 21420115 in words is "twenty-one million, four hundred twenty thousand, one hundred fifteen".