21494951497 has 2 divisors, whose sum is σ = 21494951498. Its totient is φ = 21494951496.

The previous prime is 21494951459. The next prime is 21494951509. The reversal of 21494951497 is 79415949412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16177041721 + 5317909776 = 127189^2 + 72924^2 .

It is a cyclic number.

It is not a de Polignac number, because 21494951497 - 2¹⁹ = 21494427209 is a prime.

It is not a weakly prime, because it can be changed into another prime (21494951897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10747475748 + 10747475749.

It is an arithmetic number, because the mean of its divisors is an integer number (10747475749).

Almost surely, 2^21494951497 is an apocalyptic number.

It is an amenable number.

21494951497 is a deficient number, since it is larger than the sum of its proper divisors (1).

21494951497 is an equidigital number, since it uses as much as digits as its factorization.

21494951497 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3265920, while the sum is 55.

The spelling of 21494951497 in words is "twenty-one billion, four hundred ninety-four million, nine hundred fifty-one thousand, four hundred ninety-seven".