250721 has 2 divisors, whose sum is σ = 250722. Its totient is φ = 250720.

The previous prime is 250709. The next prime is 250727. The reversal of 250721 is 127052.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 193600 + 57121 = 440^2 + 239^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-250721 is a prime.

It is a super-2 number, since 2×250721² = 125722039682, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a self number, because there is not a number n which added to its sum of digits gives 250721.

It is not a weakly prime, because it can be changed into another prime (250727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125360 + 125361.

It is an arithmetic number, because the mean of its divisors is an integer number (125361).

2²⁵⁰⁷²¹ is an apocalyptic number.

It is an amenable number.

250721 is a deficient number, since it is larger than the sum of its proper divisors (1).

250721 is an equidigital number, since it uses as much as digits as its factorization.

250721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 140, while the sum is 17.

The square root of 250721 is about 500.7204809073. The cubic root of 250721 is about 63.0565545744.

Adding to 250721 its reverse (127052), we get a palindrome (377773).

The spelling of 250721 in words is "two hundred fifty thousand, seven hundred twenty-one".