421261991 has 2 divisors, whose sum is σ = 421261992. Its totient is φ = 421261990.

The previous prime is 421261969. The next prime is 421261999. The reversal of 421261991 is 199162124.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 421261991 - 2¹⁰ = 421260967 is a prime.

It is a super-2 number, since 2×421261991² = 354923330122568162, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (421261999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210630995 + 210630996.

It is an arithmetic number, because the mean of its divisors is an integer number (210630996).

Almost surely, 2^421261991 is an apocalyptic number.

421261991 is a deficient number, since it is larger than the sum of its proper divisors (1).

421261991 is an equidigital number, since it uses as much as digits as its factorization.

421261991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7776, while the sum is 35.

The square root of 421261991 is about 20524.6678657658. The cubic root of 421261991 is about 749.6365593170.

The spelling of 421261991 in words is "four hundred twenty-one million, two hundred sixty-one thousand, nine hundred ninety-one".