21212356965 has 32 divisors (see below), whose sum is σ = 36059057280. Its totient is φ = 10627916544.

The previous prime is 21212356943. The next prime is 21212356973. The reversal of 21212356965 is 56965321212.

It is a happy number.

It is not a de Polignac number, because 21212356965 - 2¹⁵ = 21212324197 is a prime.

It is a super-2 number, since 2×21212356965² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 642879 + ... + 675068.

It is an arithmetic number, because the mean of its divisors is an integer number (1126845540).

Almost surely, 2^21212356965 is an apocalyptic number.

It is an amenable number.

21212356965 is a deficient number, since it is larger than the sum of its proper divisors (14846700315).

21212356965 is a wasteful number, since it uses less digits than its factorization.

21212356965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1318021.

The product of its digits is 194400, while the sum is 42.

The spelling of 21212356965 in words is "twenty-one billion, two hundred twelve million, three hundred fifty-six thousand, nine hundred sixty-five".