421447781 has 2 divisors, whose sum is σ = 421447782. Its totient is φ = 421447780.

The previous prime is 421447777. The next prime is 421447787. The reversal of 421447781 is 187744124.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 416568100 + 4879681 = 20410^2 + 2209^2 .

It is a cyclic number.

It is not a de Polignac number, because 421447781 - 2² = 421447777 is a prime.

It is a super-2 number, since 2×421447781² = 355236464219647922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (421447787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210723890 + 210723891.

It is an arithmetic number, because the mean of its divisors is an integer number (210723891).

Almost surely, 2^421447781 is an apocalyptic number.

It is an amenable number.

421447781 is a deficient number, since it is larger than the sum of its proper divisors (1).

421447781 is an equidigital number, since it uses as much as digits as its factorization.

421447781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 50176, while the sum is 38.

The square root of 421447781 is about 20529.1933840568. The cubic root of 421447781 is about 749.7467476792.

The spelling of 421447781 in words is "four hundred twenty-one million, four hundred forty-seven thousand, seven hundred eighty-one".