21020115 has 16 divisors (see below), whose sum is σ = 33762816. Its totient is φ = 11167200.

The previous prime is 21020093. The next prime is 21020117. The reversal of 21020115 is 51102012.

It is not a de Polignac number, because 21020115 - 2⁷ = 21019987 is a prime.

It is a super-2 number, since 2×21020115² = 883690469226450, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21020115.

It is not an unprimeable number, because it can be changed into a prime (21020117) 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 15 ways as a sum of consecutive naturals, for example, 1480 + ... + 6650.

It is an arithmetic number, because the mean of its divisors is an integer number (2110176).

Almost surely, 2^21020115 is an apocalyptic number.

21020115 is a deficient number, since it is larger than the sum of its proper divisors (12742701).

21020115 is a wasteful number, since it uses less digits than its factorization.

21020115 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5450.

The product of its (nonzero) digits is 20, while the sum is 12.

The square root of 21020115 is about 4584.7698960798. The cubic root of 21020115 is about 275.9804780353.

Adding to 21020115 its reverse (51102012), we get a palindrome (72122127).

The spelling of 21020115 in words is "twenty-one million, twenty thousand, one hundred fifteen".