21216405021235 has 8 divisors (see below), whose sum is σ = 25459805013120. Its totient is φ = 16973044691904.

The previous prime is 21216405021197. The next prime is 21216405021247. The reversal of 21216405021235 is 53212050461212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21216405021235 - 2²¹ = 21216402924083 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21216405021235.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8725827 + ... + 10889116.

It is an arithmetic number, because the mean of its divisors is an integer number (3182475626640).

Almost surely, 2^{21216405021235} is an apocalyptic number.

21216405021235 is a deficient number, since it is larger than the sum of its proper divisors (4243399991885).

21216405021235 is a wasteful number, since it uses less digits than its factorization.

21216405021235 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19831277.

The product of its (nonzero) digits is 28800, while the sum is 34.

Adding to 21216405021235 its reverse (53212050461212), we get a palindrome (74428455482447).

The spelling of 21216405021235 in words is "twenty-one trillion, two hundred sixteen billion, four hundred five million, twenty-one thousand, two hundred thirty-five".