21802131 has 12 divisors (see below), whose sum is σ = 33914608. Its totient is φ = 13416624.

The previous prime is 21802129. The next prime is 21802141. The reversal of 21802131 is 13120812.

It is not a de Polignac number, because 21802131 - 2¹ = 21802129 is a prime.

It is a super-2 number, since 2×21802131² = 950665832282322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21802141) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 93055 + ... + 93288.

Almost surely, 2^21802131 is an apocalyptic number.

21802131 is a deficient number, since it is larger than the sum of its proper divisors (12112477).

21802131 is a wasteful number, since it uses less digits than its factorization.

21802131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 186362 (or 186359 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 21802131 is about 4669.2752114220. The cubic root of 21802131 is about 279.3613462690.

Adding to 21802131 its reverse (13120812), we get a palindrome (34922943).

The spelling of 21802131 in words is "twenty-one million, eight hundred two thousand, one hundred thirty-one".