21960251 has 2 divisors, whose sum is σ = 21960252. Its totient is φ = 21960250.

The previous prime is 21960199. The next prime is 21960259. The reversal of 21960251 is 15206912.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21960251 - 2¹⁸ = 21698107 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21960251.

It is not a weakly prime, because it can be changed into another prime (21960259) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10980125 + 10980126.

It is an arithmetic number, because the mean of its divisors is an integer number (10980126).

Almost surely, 2^21960251 is an apocalyptic number.

21960251 is a deficient number, since it is larger than the sum of its proper divisors (1).

21960251 is an equidigital number, since it uses as much as digits as its factorization.

21960251 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 21960251 is about 4686.1765865149. The cubic root of 21960251 is about 280.0350763880.

The spelling of 21960251 in words is "twenty-one million, nine hundred sixty thousand, two hundred fifty-one".