251221252121201 has 2 divisors, whose sum is σ = 251221252121202. Its totient is φ = 251221252121200.

The previous prime is 251221252121107. The next prime is 251221252121209. The reversal of 251221252121201 is 102121252122152.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 140958630760000 + 110262621361201 = 11872600^2 + 10500601^2 .

It is a cyclic number.

It is not a de Polignac number, because 251221252121201 - 2¹⁸ = 251221251859057 is a prime.

It is a super-2 number, since 2×251221252121201² (a number of 30 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (251221252121209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125610626060600 + 125610626060601.

It is an arithmetic number, because the mean of its divisors is an integer number (125610626060601).

Almost surely, 2^{251221252121201} is an apocalyptic number.

It is an amenable number.

251221252121201 is a deficient number, since it is larger than the sum of its proper divisors (1).

251221252121201 is an equidigital number, since it uses as much as digits as its factorization.

251221252121201 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3200, while the sum is 29.

The spelling of 251221252121201 in words is "two hundred fifty-one trillion, two hundred twenty-one billion, two hundred fifty-two million, one hundred twenty-one thousand, two hundred one".