21495927749 has 2 divisors, whose sum is σ = 21495927750. Its totient is φ = 21495927748.

The previous prime is 21495927743. The next prime is 21495927751. The reversal of 21495927749 is 94772959412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19642022500 + 1853905249 = 140150^2 + 43057^2 .

It is a cyclic number.

It is not a de Polignac number, because 21495927749 - 2¹² = 21495923653 is a prime.

Together with 21495927751, 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 (21495927743) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10747963874 + 10747963875.

It is an arithmetic number, because the mean of its divisors is an integer number (10747963875).

Almost surely, 2^21495927749 is an apocalyptic number.

It is an amenable number.

21495927749 is a deficient number, since it is larger than the sum of its proper divisors (1).

21495927749 is an equidigital number, since it uses as much as digits as its factorization.

21495927749 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11430720, while the sum is 59.

The spelling of 21495927749 in words is "twenty-one billion, four hundred ninety-five million, nine hundred twenty-seven thousand, seven hundred forty-nine".