21012715 has 8 divisors (see below), whose sum is σ = 25298208. Its totient is φ = 16754880.

The previous prime is 21012701. The next prime is 21012737. The reversal of 21012715 is 51721012.

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

It is not a de Polignac number, because 21012715 - 2⁵ = 21012683 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21012692 and 21012701.

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, 5202 + ... + 8311.

It is an arithmetic number, because the mean of its divisors is an integer number (3162276).

Almost surely, 2^21012715 is an apocalyptic number.

21012715 is a deficient number, since it is larger than the sum of its proper divisors (4285493).

21012715 is a wasteful number, since it uses less digits than its factorization.

21012715 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13829.

The product of its (nonzero) digits is 140, while the sum is 19.

The square root of 21012715 is about 4583.9628052592. The cubic root of 21012715 is about 275.9480885005.

Adding to 21012715 its reverse (51721012), we get a palindrome (72733727).

The spelling of 21012715 in words is "twenty-one million, twelve thousand, seven hundred fifteen".