21005242434 has 64 divisors (see below), whose sum is σ = 51234439680. Its totient is φ = 6326145360.

The previous prime is 21005242411. The next prime is 21005242451. The reversal of 21005242434 is 43424250012.

21005242434 is a `hidden beast` number, since 2 + 100 + 524 + 2 + 4 + 34 = 666.

It is a super-2 number, since 2×21005242434² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 21005242398 and 21005242407.

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, 11652 + ... + 205295.

It is an arithmetic number, because the mean of its divisors is an integer number (800538120).

Almost surely, 2^21005242434 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21005242434, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25617219840).

21005242434 is an abundant number, since it is smaller than the sum of its proper divisors (30229197246).

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

21005242434 is a wasteful number, since it uses less digits than its factorization.

21005242434 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 217132 (or 217126 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 27.

Adding to 21005242434 its reverse (43424250012), we get a palindrome (64429492446).

The spelling of 21005242434 in words is "twenty-one billion, five million, two hundred forty-two thousand, four hundred thirty-four".