21887161 has 4 divisors (see below), whose sum is σ = 21907024. Its totient is φ = 21867300.

The previous prime is 21887149. The next prime is 21887167. The reversal of 21887161 is 16178812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21887161 - 2⁹ = 21886649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21887167) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8175 + ... + 10516.

It is an arithmetic number, because the mean of its divisors is an integer number (5476756).

Almost surely, 2^21887161 is an apocalyptic number.

It is an amenable number.

21887161 is a deficient number, since it is larger than the sum of its proper divisors (19863).

21887161 is a wasteful number, since it uses less digits than its factorization.

21887161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19862.

The product of its digits is 5376, while the sum is 34.

The square root of 21887161 is about 4678.3716184160. The cubic root of 21887161 is about 279.7240521145.

The spelling of 21887161 in words is "twenty-one million, eight hundred eighty-seven thousand, one hundred sixty-one".