42388921 has 2 divisors, whose sum is σ = 42388922. Its totient is φ = 42388920.

The previous prime is 42388919. The next prime is 42388949. The reversal of 42388921 is 12988324.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 25050025 + 17338896 = 5005^2 + 4164^2 .

It is a cyclic number.

It is not a de Polignac number, because 42388921 - 2¹ = 42388919 is a prime.

Together with 42388919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (42388721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21194460 + 21194461.

It is an arithmetic number, because the mean of its divisors is an integer number (21194461).

Almost surely, 2^42388921 is an apocalyptic number.

It is an amenable number.

42388921 is a deficient number, since it is larger than the sum of its proper divisors (1).

42388921 is an equidigital number, since it uses as much as digits as its factorization.

42388921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27648, while the sum is 37.

The square root of 42388921 is about 6510.6774609099. The cubic root of 42388921 is about 348.6723059328.

The spelling of 42388921 in words is "forty-two million, three hundred eighty-eight thousand, nine hundred twenty-one".