21275787473 has 2 divisors, whose sum is σ = 21275787474. Its totient is φ = 21275787472.

The previous prime is 21275787443. The next prime is 21275787493. The reversal of 21275787473 is 37478757212.

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., 21224993344 + 50794129 = 145688^2 + 7127^2 .

It is a cyclic number.

It is not a de Polignac number, because 21275787473 - 2²⁶ = 21208678609 is a prime.

It is not a weakly prime, because it can be changed into another prime (21275787443) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10637893736 + 10637893737.

It is an arithmetic number, because the mean of its divisors is an integer number (10637893737).

Almost surely, 2^21275787473 is an apocalyptic number.

It is an amenable number.

21275787473 is a deficient number, since it is larger than the sum of its proper divisors (1).

21275787473 is an equidigital number, since it uses as much as digits as its factorization.

21275787473 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4609920, while the sum is 53.

The spelling of 21275787473 in words is "twenty-one billion, two hundred seventy-five million, seven hundred eighty-seven thousand, four hundred seventy-three".