21261356205342 has 64 divisors (see below), whose sum is σ = 47074705666560. Its totient is φ = 6347643926400.

The previous prime is 21261356205337. The next prime is 21261356205389. The reversal of 21261356205342 is 24350265316212.

It is a junction number, because it is equal to n+sod(n) for n = 21261356205294 and 21261356205303.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5108748 + ... + 8283840.

It is an arithmetic number, because the mean of its divisors is an integer number (735542276040).

Almost surely, 2^{21261356205342} is an apocalyptic number.

21261356205342 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 21261356205342, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23537352833280).

21261356205342 is an abundant number, since it is smaller than the sum of its proper divisors (25813349461218).

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

21261356205342 is a wasteful number, since it uses less digits than its factorization.

21261356205342 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3176609.

The product of its (nonzero) digits is 518400, while the sum is 42.

The spelling of 21261356205342 in words is "twenty-one trillion, two hundred sixty-one billion, three hundred fifty-six million, two hundred five thousand, three hundred forty-two".