21150420391 has 2 divisors, whose sum is σ = 21150420392. Its totient is φ = 21150420390.

The previous prime is 21150420377. The next prime is 21150420419. The reversal of 21150420391 is 19302405112.

It is an a-pointer prime, because the next prime (21150420419) can be obtained adding 21150420391 to its sum of digits (28).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21150420391 - 2¹¹ = 21150418343 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21150460391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10575210195 + 10575210196.

It is an arithmetic number, because the mean of its divisors is an integer number (10575210196).

Almost surely, 2^21150420391 is an apocalyptic number.

21150420391 is a deficient number, since it is larger than the sum of its proper divisors (1).

21150420391 is an equidigital number, since it uses as much as digits as its factorization.

21150420391 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 28.

The spelling of 21150420391 in words is "twenty-one billion, one hundred fifty million, four hundred twenty thousand, three hundred ninety-one".