21881097 has 60 divisors (see below), whose sum is σ = 39312900. Its totient is φ = 12083904.

The previous prime is 21881089. The next prime is 21881131. The reversal of 21881097 is 79018812.

It can be written as a sum of positive squares in 2 ways, for example, as 11148921 + 10732176 = 3339^2 + 3276^2 .

It is not a de Polignac number, because 21881097 - 2³ = 21881089 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21881017) 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 59 ways as a sum of consecutive naturals, for example, 146779 + ... + 146927.

It is an arithmetic number, because the mean of its divisors is an integer number (655215).

Almost surely, 2^21881097 is an apocalyptic number.

21881097 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21881097 is a deficient number, since it is larger than the sum of its proper divisors (17431803).

21881097 is a wasteful number, since it uses less digits than its factorization.

21881097 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212 (or 196 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 21881097 is about 4677.7234847733. The cubic root of 21881097 is about 279.6982165219.

The spelling of 21881097 in words is "twenty-one million, eight hundred eighty-one thousand, ninety-seven".