11951957921 has 2 divisors, whose sum is σ = 11951957922. Its totient is φ = 11951957920.

The previous prime is 11951957909. The next prime is 11951957939. The reversal of 11951957921 is 12975915911.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11889721600 + 62236321 = 109040^2 + 7889^2 .

It is a cyclic number.

It is not a de Polignac number, because 11951957921 - 2¹⁴ = 11951941537 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 11951957921.

It is not a weakly prime, because it can be changed into another prime (11951957971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5975978960 + 5975978961.

It is an arithmetic number, because the mean of its divisors is an integer number (5975978961).

Almost surely, 2^11951957921 is an apocalyptic number.

It is an amenable number.

11951957921 is a deficient number, since it is larger than the sum of its proper divisors (1).

11951957921 is an equidigital number, since it uses as much as digits as its factorization.

11951957921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 255150, while the sum is 50.

The spelling of 11951957921 in words is "eleven billion, nine hundred fifty-one million, nine hundred fifty-seven thousand, nine hundred twenty-one".