21827691 has 32 divisors (see below), whose sum is σ = 34075200. Its totient is φ = 13789440.

The previous prime is 21827683. The next prime is 21827717. The reversal of 21827691 is 19672812.

It is not a de Polignac number, because 21827691 - 2³ = 21827683 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21827651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 47535 + ... + 47991.

It is an arithmetic number, because the mean of its divisors is an integer number (1064850).

Almost surely, 2^21827691 is an apocalyptic number.

21827691 is a deficient number, since it is larger than the sum of its proper divisors (12247509).

21827691 is a wasteful number, since it uses less digits than its factorization.

21827691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 556 (or 550 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 21827691 is about 4672.0114511846. The cubic root of 21827691 is about 279.4704745528.

The spelling of 21827691 in words is "twenty-one million, eight hundred twenty-seven thousand, six hundred ninety-one".