21261010165242 has 16 divisors (see below), whose sum is σ = 42532595365152. Its totient is φ = 7085240882640.

The previous prime is 21261010165159. The next prime is 21261010165267. The reversal of 21261010165242 is 24256101016212.

It is a happy number.

It is a super-2 number, since 2×21261010165242² (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, 440600308 + ... + 440648559.

It is an arithmetic number, because the mean of its divisors is an integer number (2658287210322).

Almost surely, 2^{21261010165242} is an apocalyptic number.

21261010165242 is an abundant number, since it is smaller than the sum of its proper divisors (21271585199910).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21261010165242 is a wasteful number, since it uses less digits than its factorization.

21261010165242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 881252893.

The product of its (nonzero) digits is 11520, while the sum is 33.

The spelling of 21261010165242 in words is "twenty-one trillion, two hundred sixty-one billion, ten million, one hundred sixty-five thousand, two hundred forty-two".