21220020431 has 2 divisors, whose sum is σ = 21220020432. Its totient is φ = 21220020430.

The previous prime is 21220020427. The next prime is 21220020433. The reversal of 21220020431 is 13402002212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21220020431 - 2² = 21220020427 is a prime.

It is a super-2 number, since 2×21220020431² (a number of 21 digits) contains 22 as substring.

Together with 21220020433, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21220020433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610010215 + 10610010216.

It is an arithmetic number, because the mean of its divisors is an integer number (10610010216).

Almost surely, 2^21220020431 is an apocalyptic number.

21220020431 is a deficient number, since it is larger than the sum of its proper divisors (1).

21220020431 is an equidigital number, since it uses as much as digits as its factorization.

21220020431 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 192, while the sum is 17.

Adding to 21220020431 its reverse (13402002212), we get a palindrome (34622022643).

The spelling of 21220020431 in words is "twenty-one billion, two hundred twenty million, twenty thousand, four hundred thirty-one".