20406121291 has 2 divisors, whose sum is σ = 20406121292. Its totient is φ = 20406121290.

The previous prime is 20406121273. The next prime is 20406121313. The reversal of 20406121291 is 19212160402.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20406121291 - 2¹³ = 20406113099 is a prime.

It is a super-2 number, since 2×20406121291² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20406121231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10203060645 + 10203060646.

It is an arithmetic number, because the mean of its divisors is an integer number (10203060646).

Almost surely, 2^20406121291 is an apocalyptic number.

20406121291 is a deficient number, since it is larger than the sum of its proper divisors (1).

20406121291 is an equidigital number, since it uses as much as digits as its factorization.

20406121291 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 28.

Adding to 20406121291 its reverse (19212160402), we get a palindrome (39618281693).

The spelling of 20406121291 in words is "twenty billion, four hundred six million, one hundred twenty-one thousand, two hundred ninety-one".