21261216512654 has 8 divisors (see below), whose sum is σ = 33767814461328. Its totient is φ = 10005278358880.

The previous prime is 21261216512593. The next prime is 21261216512663. The reversal of 21261216512654 is 45621561216212.

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

It is a super-2 number, since 2×21261216512654² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

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, 312664948682 + ... + 312664948749.

It is an arithmetic number, because the mean of its divisors is an integer number (4220976807666).

Almost surely, 2^{21261216512654} is an apocalyptic number.

21261216512654 is a deficient number, since it is larger than the sum of its proper divisors (12506597948674).

21261216512654 is a wasteful number, since it uses less digits than its factorization.

21261216512654 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 625329897450.

The product of its digits is 345600, while the sum is 44.

Adding to 21261216512654 its reverse (45621561216212), we get a palindrome (66882777728866).

The spelling of 21261216512654 in words is "twenty-one trillion, two hundred sixty-one billion, two hundred sixteen million, five hundred twelve thousand, six hundred fifty-four".