21896181 has 6 divisors (see below), whose sum is σ = 31627830. Its totient is φ = 14597448.

The previous prime is 21896179. The next prime is 21896191. The reversal of 21896181 is 18169812.

It can be written as a sum of positive squares in only one way, i.e., 21762225 + 133956 = 4665^2 + 366^2 .

It is not a de Polignac number, because 21896181 - 2¹ = 21896179 is a prime.

It is a super-2 number, since 2×21896181² = 958885484769522, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21896191) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1216446 + ... + 1216463.

It is an arithmetic number, because the mean of its divisors is an integer number (5271305).

Almost surely, 2^21896181 is an apocalyptic number.

It is an amenable number.

21896181 is a deficient number, since it is larger than the sum of its proper divisors (9731649).

21896181 is a wasteful number, since it uses less digits than its factorization.

21896181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2432915 (or 2432912 counting only the distinct ones).

The product of its digits is 6912, while the sum is 36.

The square root of 21896181 is about 4679.3355297521. The cubic root of 21896181 is about 279.7624728798.

The spelling of 21896181 in words is "twenty-one million, eight hundred ninety-six thousand, one hundred eighty-one".