21783815449 has 32 divisors (see below), whose sum is σ = 24520164480. Its totient is φ = 19185100800.

The previous prime is 21783815429. The next prime is 21783815461. The reversal of 21783815449 is 94451838712.

It is not a de Polignac number, because 21783815449 - 2⁷ = 21783815321 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21783815396 and 21783815405.

It is not an unprimeable number, because it can be changed into a prime (21783815429) 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, 18444639 + ... + 18445819.

It is an arithmetic number, because the mean of its divisors is an integer number (766255140).

Almost surely, 2^21783815449 is an apocalyptic number.

It is an amenable number.

21783815449 is a deficient number, since it is larger than the sum of its proper divisors (2736349031).

21783815449 is a wasteful number, since it uses less digits than its factorization.

21783815449 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1641.

The product of its digits is 1935360, while the sum is 52.

The spelling of 21783815449 in words is "twenty-one billion, seven hundred eighty-three million, eight hundred fifteen thousand, four hundred forty-nine".