11631821921 has 2 divisors, whose sum is σ = 11631821922. Its totient is φ = 11631821920.

The previous prime is 11631821909. The next prime is 11631821933. The reversal of 11631821921 is 12912813611.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (11631821909) and next prime (11631821933).

It can be written as a sum of positive squares in only one way, i.e., 8057575696 + 3574246225 = 89764^2 + 59785^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11631821921 is a prime.

It is a super-2 number, since 2×11631821921² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (11631821951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5815910960 + 5815910961.

It is an arithmetic number, because the mean of its divisors is an integer number (5815910961).

Almost surely, 2^11631821921 is an apocalyptic number.

It is an amenable number.

11631821921 is a deficient number, since it is larger than the sum of its proper divisors (1).

11631821921 is an equidigital number, since it uses as much as digits as its factorization.

11631821921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5184, while the sum is 35.

The spelling of 11631821921 in words is "eleven billion, six hundred thirty-one million, eight hundred twenty-one thousand, nine hundred twenty-one".