251903406403421 has 2 divisors, whose sum is σ = 251903406403422. Its totient is φ = 251903406403420.

The previous prime is 251903406403343. The next prime is 251903406403433. The reversal of 251903406403421 is 124304604309152.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 248004700867225 + 3898705536196 = 15748165^2 + 1974514^2 .

It is a cyclic number.

It is not a de Polignac number, because 251903406403421 - 2¹⁴ = 251903406387037 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (251903406103421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125951703201710 + 125951703201711.

It is an arithmetic number, because the mean of its divisors is an integer number (125951703201711).

Almost surely, 2^{251903406403421} is an apocalyptic number.

It is an amenable number.

251903406403421 is a deficient number, since it is larger than the sum of its proper divisors (1).

251903406403421 is an equidigital number, since it uses as much as digits as its factorization.

251903406403421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 622080, while the sum is 44.

The spelling of 251903406403421 in words is "two hundred fifty-one trillion, nine hundred three billion, four hundred six million, four hundred three thousand, four hundred twenty-one".