21261215621434 has 16 divisors (see below), whose sum is σ = 32000606493480. Its totient is φ = 10594395302400.

The previous prime is 21261215621419. The next prime is 21261215621483. The reversal of 21261215621434 is 43412651216212.

It can be written as a sum of positive squares in 4 ways, for example, as 14253531898225 + 7007683723209 = 3775385^2 + 2647203^2 .

It is a super-2 number, since 2×21261215621434² (a number of 27 digits) contains 22 as substring.

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, 11250699 + ... + 13003870.

Almost surely, 2^{21261215621434} is an apocalyptic number.

21261215621434 is a deficient number, since it is larger than the sum of its proper divisors (10739390872046).

21261215621434 is a wasteful number, since it uses less digits than its factorization.

21261215621434 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24256065.

The product of its digits is 138240, while the sum is 40.

Adding to 21261215621434 its reverse (43412651216212), we get a palindrome (64673866837646).

The spelling of 21261215621434 in words is "twenty-one trillion, two hundred sixty-one billion, two hundred fifteen million, six hundred twenty-one thousand, four hundred thirty-four".