21940951397 has 2 divisors, whose sum is σ = 21940951398. Its totient is φ = 21940951396.

The previous prime is 21940951387. The next prime is 21940951489. The reversal of 21940951397 is 79315904912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18727648801 + 3213302596 = 136849^2 + 56686^2 .

It is a cyclic number.

It is not a de Polignac number, because 21940951397 - 2¹⁴ = 21940935013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21940951337) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10970475698 + 10970475699.

It is an arithmetic number, because the mean of its divisors is an integer number (10970475699).

Almost surely, 2^21940951397 is an apocalyptic number.

It is an amenable number.

21940951397 is a deficient number, since it is larger than the sum of its proper divisors (1).

21940951397 is an equidigital number, since it uses as much as digits as its factorization.

21940951397 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 612360, while the sum is 50.

The spelling of 21940951397 in words is "twenty-one billion, nine hundred forty million, nine hundred fifty-one thousand, three hundred ninety-seven".