20315252215421 has 4 divisors (see below), whose sum is σ = 20345259974172. Its totient is φ = 20285244456672.

The previous prime is 20315252215283. The next prime is 20315252215439. The reversal of 20315252215421 is 12451225251302.

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

It can be written as a sum of positive squares in 2 ways, for example, as 19983805605625 + 331446609796 = 4470325^2 + 575714^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20315252215421 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20315252215471) 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, 15003878360 + ... + 15003879713.

It is an arithmetic number, because the mean of its divisors is an integer number (5086314993543).

Almost surely, 2^{20315252215421} is an apocalyptic number.

It is an amenable number.

20315252215421 is a deficient number, since it is larger than the sum of its proper divisors (30007758751).

20315252215421 is an equidigital number, since it uses as much as digits as its factorization.

20315252215421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30007758750.

The product of its (nonzero) digits is 48000, while the sum is 35.

Adding to 20315252215421 its reverse (12451225251302), we get a palindrome (32766477466723).

The spelling of 20315252215421 in words is "twenty trillion, three hundred fifteen billion, two hundred fifty-two million, two hundred fifteen thousand, four hundred twenty-one".