21511490069 has 2 divisors, whose sum is σ = 21511490070. Its totient is φ = 21511490068.

The previous prime is 21511490047. The next prime is 21511490101. The reversal of 21511490069 is 96009411512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21174033169 + 337456900 = 145513^2 + 18370^2 .

It is a cyclic number.

It is not a de Polignac number, because 21511490069 - 2¹⁶ = 21511424533 is a prime.

It is a super-2 number, since 2×21511490069² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21516490069) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10755745034 + 10755745035.

It is an arithmetic number, because the mean of its divisors is an integer number (10755745035).

Almost surely, 2^21511490069 is an apocalyptic number.

It is an amenable number.

21511490069 is a deficient number, since it is larger than the sum of its proper divisors (1).

21511490069 is an equidigital number, since it uses as much as digits as its factorization.

21511490069 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 19440, while the sum is 38.

The spelling of 21511490069 in words is "twenty-one billion, five hundred eleven million, four hundred ninety thousand, sixty-nine".