420721751 has 2 divisors, whose sum is σ = 420721752. Its totient is φ = 420721750.

The previous prime is 420721723. The next prime is 420721757. The reversal of 420721751 is 157127024.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 420721751 - 2²⁶ = 353612887 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (420721757) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210360875 + 210360876.

It is an arithmetic number, because the mean of its divisors is an integer number (210360876).

Almost surely, 2^420721751 is an apocalyptic number.

420721751 is a deficient number, since it is larger than the sum of its proper divisors (1).

420721751 is an equidigital number, since it uses as much as digits as its factorization.

420721751 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3920, while the sum is 29.

The square root of 420721751 is about 20511.5028947174. The cubic root of 420721751 is about 749.3159695112.

Adding to 420721751 its reverse (157127024), we get a palindrome (577848775).

The spelling of 420721751 in words is "four hundred twenty million, seven hundred twenty-one thousand, seven hundred fifty-one".