21250807 has 2 divisors, whose sum is σ = 21250808. Its totient is φ = 21250806.

The previous prime is 21250793. The next prime is 21250813. The reversal of 21250807 is 70805212.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21250807 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21250837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10625403 + 10625404.

It is an arithmetic number, because the mean of its divisors is an integer number (10625404).

Almost surely, 2^21250807 is an apocalyptic number.

21250807 is a deficient number, since it is larger than the sum of its proper divisors (1).

21250807 is an equidigital number, since it uses as much as digits as its factorization.

21250807 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1120, while the sum is 25.

The square root of 21250807 is about 4609.8597592552. The cubic root of 21250807 is about 276.9864190712.

The spelling of 21250807 in words is "twenty-one million, two hundred fifty thousand, eight hundred seven".