42420551681 has 2 divisors, whose sum is σ = 42420551682. Its totient is φ = 42420551680.

The previous prime is 42420551627. The next prime is 42420551687. The reversal of 42420551681 is 18615502424.

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., 25672050625 + 16748501056 = 160225^2 + 129416^2 .

It is a cyclic number.

It is not a de Polignac number, because 42420551681 - 2⁶ = 42420551617 is a prime.

It is a super-2 number, since 2×42420551681² (a number of 22 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (42420551687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21210275840 + 21210275841.

It is an arithmetic number, because the mean of its divisors is an integer number (21210275841).

Almost surely, 2^42420551681 is an apocalyptic number.

It is an amenable number.

42420551681 is a deficient number, since it is larger than the sum of its proper divisors (1).

42420551681 is an equidigital number, since it uses as much as digits as its factorization.

42420551681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 76800, while the sum is 38.

The spelling of 42420551681 in words is "forty-two billion, four hundred twenty million, five hundred fifty-one thousand, six hundred eighty-one".