21531021466 has 8 divisors (see below), whose sum is σ = 32297284404. Its totient is φ = 10765260000.

The previous prime is 21531021397. The next prime is 21531021481. The reversal of 21531021466 is 66412013512.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 13109105025 + 8421916441 = 114495^2 + 91771^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12136 + ... + 207868.

Almost surely, 2^21531021466 is an apocalyptic number.

21531021466 is a deficient number, since it is larger than the sum of its proper divisors (10766262938).

21531021466 is a wasteful number, since it uses less digits than its factorization.

21531021466 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 250736.

The product of its (nonzero) digits is 8640, while the sum is 31.

Adding to 21531021466 its reverse (66412013512), we get a palindrome (87943034978).

The spelling of 21531021466 in words is "twenty-one billion, five hundred thirty-one million, twenty-one thousand, four hundred sixty-six".