840427421 has 2 divisors, whose sum is σ = 840427422. Its totient is φ = 840427420.

The previous prime is 840427409. The next prime is 840427451. The reversal of 840427421 is 124724048.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 779805625 + 60621796 = 27925^2 + 7786^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-840427421 is a prime.

It is a super-2 number, since 2×840427421² = 1412636499937422482, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (840427451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 420213710 + 420213711.

It is an arithmetic number, because the mean of its divisors is an integer number (420213711).

Almost surely, 2^840427421 is an apocalyptic number.

It is an amenable number.

840427421 is a deficient number, since it is larger than the sum of its proper divisors (1).

840427421 is an equidigital number, since it uses as much as digits as its factorization.

840427421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 14336, while the sum is 32.

The square root of 840427421 is about 28990.1262674035. The cubic root of 840427421 is about 943.6988039652.

The spelling of 840427421 in words is "eight hundred forty million, four hundred twenty-seven thousand, four hundred twenty-one".