21325043646 has 24 divisors (see below), whose sum is σ = 46661733144. Its totient is φ = 7037967600.

The previous prime is 21325043633. The next prime is 21325043669. The reversal of 21325043646 is 64634052312.

21325043646 is a `hidden beast` number, since 2 + 1 + 3 + 2 + 5 + 0 + 4 + 3 + 646 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21325043646.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5863156 + ... + 5866791.

It is an arithmetic number, because the mean of its divisors is an integer number (1944238881).

Almost surely, 2^21325043646 is an apocalyptic number.

21325043646 is an abundant number, since it is smaller than the sum of its proper divisors (25336689498).

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

21325043646 is a wasteful number, since it uses less digits than its factorization.

21325043646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11730056 (or 11730053 counting only the distinct ones).

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

Adding to 21325043646 its reverse (64634052312), we get a palindrome (85959095958).

The spelling of 21325043646 in words is "twenty-one billion, three hundred twenty-five million, forty-three thousand, six hundred forty-six".