20021395831 has 2 divisors, whose sum is σ = 20021395832. Its totient is φ = 20021395830.

The previous prime is 20021395829. The next prime is 20021395883. The reversal of 20021395831 is 13859312002.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20021395831 - 2¹ = 20021395829 is a prime.

It is a super-2 number, since 2×20021395831² (a number of 21 digits) contains 22 as substring.

Together with 20021395829, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20021395631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10010697915 + 10010697916.

It is an arithmetic number, because the mean of its divisors is an integer number (10010697916).

Almost surely, 2^20021395831 is an apocalyptic number.

20021395831 is a deficient number, since it is larger than the sum of its proper divisors (1).

20021395831 is an equidigital number, since it uses as much as digits as its factorization.

20021395831 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12960, while the sum is 34.

The spelling of 20021395831 in words is "twenty billion, twenty-one million, three hundred ninety-five thousand, eight hundred thirty-one".