21493477849 has 2 divisors, whose sum is σ = 21493477850. Its totient is φ = 21493477848.

The previous prime is 21493477823. The next prime is 21493477853. The reversal of 21493477849 is 94877439412.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18959362249 + 2534115600 = 137693^2 + 50340^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21493477849 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21493477793 and 21493477802.

It is not a weakly prime, because it can be changed into another prime (21493477879) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10746738924 + 10746738925.

It is an arithmetic number, because the mean of its divisors is an integer number (10746738925).

Almost surely, 2^21493477849 is an apocalyptic number.

It is an amenable number.

21493477849 is a deficient number, since it is larger than the sum of its proper divisors (1).

21493477849 is an equidigital number, since it uses as much as digits as its factorization.

21493477849 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12192768, while the sum is 58.

The spelling of 21493477849 in words is "twenty-one billion, four hundred ninety-three million, four hundred seventy-seven thousand, eight hundred forty-nine".