421020781 has 2 divisors, whose sum is σ = 421020782. Its totient is φ = 421020780.

The previous prime is 421020731. The next prime is 421020797. The reversal of 421020781 is 187020124.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 400400100 + 20620681 = 20010^2 + 4541^2 .

It is a cyclic number.

It is not a de Polignac number, because 421020781 - 2¹³ = 421012589 is a prime.

It is a super-2 number, since 2×421020781² = 354516996067699922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (421020701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210510390 + 210510391.

It is an arithmetic number, because the mean of its divisors is an integer number (210510391).

Almost surely, 2^421020781 is an apocalyptic number.

It is an amenable number.

421020781 is a deficient number, since it is larger than the sum of its proper divisors (1).

421020781 is an equidigital number, since it uses as much as digits as its factorization.

421020781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 896, while the sum is 25.

The square root of 421020781 is about 20518.7909244185. The cubic root of 421020781 is about 749.4934541068.

The spelling of 421020781 in words is "four hundred twenty-one million, twenty thousand, seven hundred eighty-one".