21156501715 has 8 divisors (see below), whose sum is σ = 25501650048. Its totient is φ = 16849302720.

The previous prime is 21156501697. The next prime is 21156501719. The reversal of 21156501715 is 51710565112.

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

It is not a de Polignac number, because 21156501715 - 2⁹ = 21156501203 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21156501719) 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, 9486106 + ... + 9488335.

It is an arithmetic number, because the mean of its divisors is an integer number (3187706256).

Almost surely, 2^21156501715 is an apocalyptic number.

21156501715 is a deficient number, since it is larger than the sum of its proper divisors (4345148333).

21156501715 is a wasteful number, since it uses less digits than its factorization.

21156501715 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18974669.

The product of its (nonzero) digits is 10500, while the sum is 34.

The spelling of 21156501715 in words is "twenty-one billion, one hundred fifty-six million, five hundred one thousand, seven hundred fifteen".