21245402340 has 36 divisors (see below), whose sum is σ = 64444387644. Its totient is φ = 5665440576.

The previous prime is 21245402327. The next prime is 21245402363. The reversal of 21245402340 is 4320454212.

21245402340 is a `hidden beast` number, since 212 + 4 + 5 + 402 + 3 + 40 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 11487123684 + 9758278656 = 107178^2 + 98784^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 59014827 + ... + 59015186.

It is an arithmetic number, because the mean of its divisors is an integer number (1790121879).

Almost surely, 2^21245402340 is an apocalyptic number.

21245402340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21245402340 is an abundant number, since it is smaller than the sum of its proper divisors (43198985304).

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

21245402340 is a wasteful number, since it uses less digits than its factorization.

21245402340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118030028 (or 118030023 counting only the distinct ones).

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

Adding to 21245402340 its reverse (4320454212), we get a palindrome (25565856552).

The spelling of 21245402340 in words is "twenty-one billion, two hundred forty-five million, four hundred two thousand, three hundred forty".