31521013354021 has 4 divisors (see below), whose sum is σ = 31544911015200. Its totient is φ = 31497115692844.

The previous prime is 31521013354003. The next prime is 31521013354067. The reversal of 31521013354021 is 12045331012513.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 31521013354021 - 2¹¹ = 31521013351973 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 (31521013354921) 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, 11948828611 + ... + 11948831248.

It is an arithmetic number, because the mean of its divisors is an integer number (7886227753800).

Almost surely, 2^{31521013354021} is an apocalyptic number.

It is an amenable number.

31521013354021 is a deficient number, since it is larger than the sum of its proper divisors (23897661179).

31521013354021 is a wasteful number, since it uses less digits than its factorization.

31521013354021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23897661178.

The product of its (nonzero) digits is 10800, while the sum is 31.

Adding to 31521013354021 its reverse (12045331012513), we get a palindrome (43566344366534).

The spelling of 31521013354021 in words is "thirty-one trillion, five hundred twenty-one billion, thirteen million, three hundred fifty-four thousand, twenty-one".