21213631181 has 2 divisors, whose sum is σ = 21213631182. Its totient is φ = 21213631180.

The previous prime is 21213631177. The next prime is 21213631217. The reversal of 21213631181 is 18113631212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20918993956 + 294637225 = 144634^2 + 17165^2 .

It is a cyclic number.

It is not a de Polignac number, because 21213631181 - 2² = 21213631177 is a prime.

It is a super-2 number, since 2×21213631181² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21213651181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606815590 + 10606815591.

It is an arithmetic number, because the mean of its divisors is an integer number (10606815591).

Almost surely, 2^21213631181 is an apocalyptic number.

It is an amenable number.

21213631181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213631181 is an equidigital number, since it uses as much as digits as its factorization.

21213631181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1728, while the sum is 29.

The spelling of 21213631181 in words is "twenty-one billion, two hundred thirteen million, six hundred thirty-one thousand, one hundred eighty-one".