21254343660 has 144 divisors (see below), whose sum is σ = 70614415872. Its totient is φ = 5131920000.

The previous prime is 21254343637. The next prime is 21254343661. The reversal of 21254343660 is 6634345212.

21254343660 is a `hidden beast` number, since 2 + 1 + 254 + 343 + 6 + 60 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21254343661) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 475597 + ... + 518363.

It is an arithmetic number, because the mean of its divisors is an integer number (490377888).

Almost surely, 2^21254343660 is an apocalyptic number.

21254343660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21254343660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35307207936).

21254343660 is an abundant number, since it is smaller than the sum of its proper divisors (49360072212).

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

21254343660 is a wasteful number, since it uses less digits than its factorization.

21254343660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43044 (or 43039 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 36.

Adding to 21254343660 its reverse (6634345212), we get a palindrome (27888688872).

The spelling of 21254343660 in words is "twenty-one billion, two hundred fifty-four million, three hundred forty-three thousand, six hundred sixty".