21978409353 has 32 divisors (see below), whose sum is σ = 32715239040. Its totient is φ = 13043036160.

The previous prime is 21978409351. The next prime is 21978409361. The reversal of 21978409353 is 35390487912.

It is not a de Polignac number, because 21978409353 - 2¹ = 21978409351 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a junction number, because it is equal to n+sod(n) for n = 21978409296 and 21978409305.

It is not an unprimeable number, because it can be changed into a prime (21978409351) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 579493 + ... + 616253.

It is an arithmetic number, because the mean of its divisors is an integer number (1022351220).

Almost surely, 2^21978409353 is an apocalyptic number.

It is an amenable number.

21978409353 is a deficient number, since it is larger than the sum of its proper divisors (10736829687).

21978409353 is a wasteful number, since it uses less digits than its factorization.

21978409353 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37417.

The product of its (nonzero) digits is 1632960, while the sum is 51.

The spelling of 21978409353 in words is "twenty-one billion, nine hundred seventy-eight million, four hundred nine thousand, three hundred fifty-three".