21854105649 has 12 divisors (see below), whose sum is σ = 31873518976. Its totient is φ = 14427952632.

The previous prime is 21854105639. The next prime is 21854105657. The reversal of 21854105649 is 94650145812.

21854105649 is a `hidden beast` number, since 2 + 1 + 85 + 4 + 1 + 0 + 564 + 9 = 666.

It is not a de Polignac number, because 21854105649 - 2⁸ = 21854105393 is a prime.

It is a super-2 number, since 2×21854105649² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21854105639) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11786617 + ... + 11788470.

Almost surely, 2^21854105649 is an apocalyptic number.

It is an amenable number.

21854105649 is a deficient number, since it is larger than the sum of its proper divisors (10019413327).

21854105649 is a wasteful number, since it uses less digits than its factorization.

21854105649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23575196 (or 23575193 counting only the distinct ones).

The product of its (nonzero) digits is 345600, while the sum is 45.

The spelling of 21854105649 in words is "twenty-one billion, eight hundred fifty-four million, one hundred five thousand, six hundred forty-nine".