21971853 has 6 divisors (see below), whose sum is σ = 31737134. Its totient is φ = 14647896.

The previous prime is 21971849. The next prime is 21971861. The reversal of 21971853 is 35817912.

It can be written as a sum of positive squares in only one way, i.e., 20766249 + 1205604 = 4557^2 + 1098^2 .

It is not a de Polignac number, because 21971853 - 2² = 21971849 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21901853) 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 5 ways as a sum of consecutive naturals, for example, 1220650 + ... + 1220667.

Almost surely, 2^21971853 is an apocalyptic number.

It is an amenable number.

21971853 is a deficient number, since it is larger than the sum of its proper divisors (9765281).

21971853 is a wasteful number, since it uses less digits than its factorization.

21971853 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2441323 (or 2441320 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 21971853 is about 4687.4143192169. The cubic root of 21971853 is about 280.0843835804.

The spelling of 21971853 in words is "twenty-one million, nine hundred seventy-one thousand, eight hundred fifty-three".