21511439273 has 2 divisors, whose sum is σ = 21511439274. Its totient is φ = 21511439272.

The previous prime is 21511439267. The next prime is 21511439281. The reversal of 21511439273 is 37293411512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14502903184 + 7008536089 = 120428^2 + 83717^2 .

It is a cyclic number.

It is not a de Polignac number, because 21511439273 - 2⁸ = 21511439017 is a prime.

It is not a weakly prime, because it can be changed into another prime (21511439263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10755719636 + 10755719637.

It is an arithmetic number, because the mean of its divisors is an integer number (10755719637).

Almost surely, 2^21511439273 is an apocalyptic number.

It is an amenable number.

21511439273 is a deficient number, since it is larger than the sum of its proper divisors (1).

21511439273 is an equidigital number, since it uses as much as digits as its factorization.

21511439273 is an evil number, because the sum of its binary digits is even.

The product of its digits is 45360, while the sum is 38.

The spelling of 21511439273 in words is "twenty-one billion, five hundred eleven million, four hundred thirty-nine thousand, two hundred seventy-three".