42021691 has 2 divisors, whose sum is σ = 42021692. Its totient is φ = 42021690.

The previous prime is 42021689. The next prime is 42021701. The reversal of 42021691 is 19612024.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 42021691 - 2¹ = 42021689 is a prime.

Together with 42021689, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (42021641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21010845 + 21010846.

It is an arithmetic number, because the mean of its divisors is an integer number (21010846).

Almost surely, 2^42021691 is an apocalyptic number.

42021691 is a deficient number, since it is larger than the sum of its proper divisors (1).

42021691 is an equidigital number, since it uses as much as digits as its factorization.

42021691 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 42021691 is about 6482.4139793753. The cubic root of 42021691 is about 347.6624942647.

The spelling of 42021691 in words is "forty-two million, twenty-one thousand, six hundred ninety-one".