21420513515 has 4 divisors (see below), whose sum is σ = 25704616224. Its totient is φ = 17136410808.

The previous prime is 21420513497. The next prime is 21420513533. The reversal of 21420513515 is 51531502412.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21420513497) and next prime (21420513533).

It is a cyclic number.

It is not a de Polignac number, because 21420513515 - 2²⁶ = 21353404651 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2142051347 + ... + 2142051356.

It is an arithmetic number, because the mean of its divisors is an integer number (6426154056).

Almost surely, 2^21420513515 is an apocalyptic number.

21420513515 is a deficient number, since it is larger than the sum of its proper divisors (4284102709).

21420513515 is an equidigital number, since it uses as much as digits as its factorization.

21420513515 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4284102708.

The product of its (nonzero) digits is 6000, while the sum is 29.

The spelling of 21420513515 in words is "twenty-one billion, four hundred twenty million, five hundred thirteen thousand, five hundred fifteen".