21780387452 has 24 divisors (see below), whose sum is σ = 38894979312. Its totient is φ = 10668960000.

The previous prime is 21780387449. The next prime is 21780387457. The reversal of 21780387452 is 25478308712.

It is a junction number, because it is equal to n+sod(n) for n = 21780387397 and 21780387406.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21780387457) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 116573 + ... + 239060.

It is an arithmetic number, because the mean of its divisors is an integer number (1620624138).

Almost surely, 2^21780387452 is an apocalyptic number.

It is an amenable number.

21780387452 is a deficient number, since it is larger than the sum of its proper divisors (17114591860).

21780387452 is a wasteful number, since it uses less digits than its factorization.

21780387452 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 355949 (or 355947 counting only the distinct ones).

The product of its (nonzero) digits is 752640, while the sum is 47.

The spelling of 21780387452 in words is "twenty-one billion, seven hundred eighty million, three hundred eighty-seven thousand, four hundred fifty-two".