21212220949 has 2 divisors, whose sum is σ = 21212220950. Its totient is φ = 21212220948.

The previous prime is 21212220943. The next prime is 21212221007. The reversal of 21212220949 is 94902221212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20766251025 + 445969924 = 144105^2 + 21118^2 .

It is a cyclic number.

It is not a de Polignac number, because 21212220949 - 2⁹ = 21212220437 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21212220943) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606110474 + 10606110475.

It is an arithmetic number, because the mean of its divisors is an integer number (10606110475).

Almost surely, 2^21212220949 is an apocalyptic number.

It is an amenable number.

21212220949 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212220949 is an equidigital number, since it uses as much as digits as its factorization.

21212220949 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10368, while the sum is 34.

The spelling of 21212220949 in words is "twenty-one billion, two hundred twelve million, two hundred twenty thousand, nine hundred forty-nine".