21212863961 has 2 divisors, whose sum is σ = 21212863962. Its totient is φ = 21212863960.

The previous prime is 21212863949. The next prime is 21212863963. The reversal of 21212863961 is 16936821212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17813973961 + 3398890000 = 133469^2 + 58300^2 .

It is a cyclic number.

It is not a de Polignac number, because 21212863961 - 2⁶ = 21212863897 is a prime.

Together with 21212863963, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21212863963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606431980 + 10606431981.

It is an arithmetic number, because the mean of its divisors is an integer number (10606431981).

Almost surely, 2^21212863961 is an apocalyptic number.

It is an amenable number.

21212863961 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212863961 is an equidigital number, since it uses as much as digits as its factorization.

21212863961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 62208, while the sum is 41.

The spelling of 21212863961 in words is "twenty-one billion, two hundred twelve million, eight hundred sixty-three thousand, nine hundred sixty-one".