21015715207 has 8 divisors (see below), whose sum is σ = 21706509440. Its totient is φ = 20325725280.

The previous prime is 21015715117. The next prime is 21015715213. The reversal of 21015715207 is 70251751012.

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

It is a cyclic number.

It is not a de Polignac number, because 21015715207 - 2¹⁵ = 21015682439 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21015715247) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 147732 + ... + 252697.

It is an arithmetic number, because the mean of its divisors is an integer number (2713313680).

Almost surely, 2^21015715207 is an apocalyptic number.

21015715207 is a deficient number, since it is larger than the sum of its proper divisors (690794233).

21015715207 is a wasteful number, since it uses less digits than its factorization.

21015715207 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 402153.

The product of its (nonzero) digits is 4900, while the sum is 31.

The spelling of 21015715207 in words is "twenty-one billion, fifteen million, seven hundred fifteen thousand, two hundred seven".