21115867969 has 9 divisors (see below), whose sum is σ = 24564539937. Its totient is φ = 18098443524.

The previous prime is 21115867967. The next prime is 21115868009. The reversal of 21115867969 is 96976851112.

It is a happy number.

The square root of 21115867969 is 145313.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 21115867969 - 2¹ = 21115867967 is a prime.

It is a super-2 number, since 2×21115867969² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21115867963) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1006812 + ... + 1027570.

Almost surely, 2^21115867969 is an apocalyptic number.

21115867969 is the 145313-rd square number.

21115867969 is the 72657-th centered octagonal number.

It is an amenable number.

21115867969 is a deficient number, since it is larger than the sum of its proper divisors (3448671968).

21115867969 is an frugal number, since it uses more digits than its factorization.

21115867969 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41532 (or 20766 counting only the distinct ones).

The product of its digits is 1632960, while the sum is 55.

The spelling of 21115867969 in words is "twenty-one billion, one hundred fifteen million, eight hundred sixty-seven thousand, nine hundred sixty-nine".