21877641 has 16 divisors (see below), whose sum is σ = 33203520. Its totient is φ = 14228640.

The previous prime is 21877637. The next prime is 21877649. The reversal of 21877641 is 14677812.

21877641 = 284² + 285² + ... + 445².

21877641 is a `hidden beast` number, since 2 + 1 + 8 + 7 + 7 + 641 = 666.

It is not a de Polignac number, because 21877641 - 2² = 21877637 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21877596 and 21877605.

It is not an unprimeable number, because it can be changed into a prime (21877649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8775 + ... + 10988.

It is an arithmetic number, because the mean of its divisors is an integer number (2075220).

Almost surely, 2^21877641 is an apocalyptic number.

It is an amenable number.

21877641 is a deficient number, since it is larger than the sum of its proper divisors (11325879).

21877641 is a wasteful number, since it uses less digits than its factorization.

21877641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19813 (or 19807 counting only the distinct ones).

The product of its digits is 18816, while the sum is 36.

The square root of 21877641 is about 4677.3540597222. The cubic root of 21877641 is about 279.6834901436.

The spelling of 21877641 in words is "twenty-one million, eight hundred seventy-seven thousand, six hundred forty-one".