20621244231515 has 4 divisors (see below), whose sum is σ = 24745493077824. Its totient is φ = 16496995385208.

The previous prime is 20621244231481. The next prime is 20621244231517. The reversal of 20621244231515 is 51513244212602.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20621244231515 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20621244231517) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2062124423147 + ... + 2062124423156.

It is an arithmetic number, because the mean of its divisors is an integer number (6186373269456).

Almost surely, 2^{20621244231515} is an apocalyptic number.

20621244231515 is a deficient number, since it is larger than the sum of its proper divisors (4124248846309).

20621244231515 is an equidigital number, since it uses as much as digits as its factorization.

20621244231515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4124248846308.

The product of its (nonzero) digits is 115200, while the sum is 38.

The spelling of 20621244231515 in words is "twenty trillion, six hundred twenty-one billion, two hundred forty-four million, two hundred thirty-one thousand, five hundred fifteen".