21771202131 has 12 divisors (see below), whose sum is σ = 35939762352. Its totient is φ = 12440686896.

The previous prime is 21771202121. The next prime is 21771202139. The reversal of 21771202131 is 13120217712.

It is not a de Polignac number, because 21771202131 - 2¹⁰ = 21771201107 is a prime.

It is a super-2 number, since 2×21771202131² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21771202095 and 21771202104.

It is not an unprimeable number, because it can be changed into a prime (21771202139) 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, 172787256 + ... + 172787381.

It is an arithmetic number, because the mean of its divisors is an integer number (2994980196).

Almost surely, 2^21771202131 is an apocalyptic number.

21771202131 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21771202131 is a deficient number, since it is larger than the sum of its proper divisors (14168560221).

21771202131 is a wasteful number, since it uses less digits than its factorization.

21771202131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 345574650 (or 345574647 counting only the distinct ones).

The product of its (nonzero) digits is 1176, while the sum is 27.

Adding to 21771202131 its reverse (13120217712), we get a palindrome (34891419843).

The spelling of 21771202131 in words is "twenty-one billion, seven hundred seventy-one million, two hundred two thousand, one hundred thirty-one".