21015005 has 16 divisors (see below), whose sum is σ = 27675648. Its totient is φ = 15192000.

The previous prime is 21014999. The next prime is 21015011. The reversal of 21015005 is 50051012.

It is an interprime number because it is at equal distance from previous prime (21014999) and next prime (21015011).

It is not a de Polignac number, because 21015005 - 2⁴ = 21014989 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8900 + ... + 11010.

It is an arithmetic number, because the mean of its divisors is an integer number (1729728).

Almost surely, 2^21015005 is an apocalyptic number.

It is an amenable number.

21015005 is a deficient number, since it is larger than the sum of its proper divisors (6660643).

21015005 is a wasteful number, since it uses less digits than its factorization.

21015005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2308.

The product of its (nonzero) digits is 50, while the sum is 14.

The square root of 21015005 is about 4584.2125823308. The cubic root of 21015005 is about 275.9581125608.

Adding to 21015005 its reverse (50051012), we get a palindrome (71066017).

The spelling of 21015005 in words is "twenty-one million, fifteen thousand, five".