21457402236 has 72 divisors (see below), whose sum is σ = 56730046464. Its totient is φ = 6825503520.

The previous prime is 21457402229. The next prime is 21457402283. The reversal of 21457402236 is 63220475412.

21457402236 is a `hidden beast` number, since 2 + 14 + 5 + 7 + 402 + 236 = 666.

It is a super-2 number, since 2×21457402236² (a number of 21 digits) contains 22 as substring.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21457402236.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 326805 + ... + 386931.

It is an arithmetic number, because the mean of its divisors is an integer number (787917312).

Almost surely, 2^21457402236 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21457402236, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28365023232).

21457402236 is an abundant number, since it is smaller than the sum of its proper divisors (35272644228).

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

21457402236 is a wasteful number, since it uses less digits than its factorization.

21457402236 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60591 (or 60586 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 36.

Adding to 21457402236 its reverse (63220475412), we get a palindrome (84677877648).

The spelling of 21457402236 in words is "twenty-one billion, four hundred fifty-seven million, four hundred two thousand, two hundred thirty-six".