21215682949 has 2 divisors, whose sum is σ = 21215682950. Its totient is φ = 21215682948.

The previous prime is 21215682911. The next prime is 21215682979. The reversal of 21215682949 is 94928651212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16491182724 + 4724500225 = 128418^2 + 68735^2 .

It is a cyclic number.

It is not a de Polignac number, because 21215682949 - 2¹⁹ = 21215158661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21215682979) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10607841474 + 10607841475.

It is an arithmetic number, because the mean of its divisors is an integer number (10607841475).

Almost surely, 2^21215682949 is an apocalyptic number.

It is an amenable number.

21215682949 is a deficient number, since it is larger than the sum of its proper divisors (1).

21215682949 is an equidigital number, since it uses as much as digits as its factorization.

21215682949 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 622080, while the sum is 49.

The spelling of 21215682949 in words is "twenty-one billion, two hundred fifteen million, six hundred eighty-two thousand, nine hundred forty-nine".