21405216191952 has 20 divisors (see below), whose sum is σ = 55296808496000. Its totient is φ = 7135072063968.

The previous prime is 21405216191911. The next prime is 21405216191999. The reversal of 21405216191952 is 25919161250412.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (48), and also a Moran number because the ratio is a prime number: 445942003999 = 21405216191952 / (2 + 1 + 4 + 0 + 5 + 2 + 1 + 6 + 1 + 9 + 1 + 9 + 5 + 2).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 222971001952 + ... + 222971002047.

It is an arithmetic number, because the mean of its divisors is an integer number (2764840424800).

Almost surely, 2^{21405216191952} is an apocalyptic number.

It is an amenable number.

21405216191952 is an abundant number, since it is smaller than the sum of its proper divisors (33891592304048).

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

21405216191952 is a wasteful number, since it uses less digits than its factorization.

21405216191952 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 445942004010 (or 445942004004 counting only the distinct ones).

The product of its (nonzero) digits is 388800, while the sum is 48.

The spelling of 21405216191952 in words is "twenty-one trillion, four hundred five billion, two hundred sixteen million, one hundred ninety-one thousand, nine hundred fifty-two".