42784921 has 2 divisors, whose sum is σ = 42784922. Its totient is φ = 42784920.

The previous prime is 42784897. The next prime is 42784933. The reversal of 42784921 is 12948724.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 41744521 + 1040400 = 6461^2 + 1020^2 .

It is a cyclic number.

It is not a de Polignac number, because 42784921 - 2¹³ = 42776729 is a prime.

It is not a weakly prime, because it can be changed into another prime (42784421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21392460 + 21392461.

It is an arithmetic number, because the mean of its divisors is an integer number (21392461).

Almost surely, 2^42784921 is an apocalyptic number.

It is an amenable number.

42784921 is a deficient number, since it is larger than the sum of its proper divisors (1).

42784921 is an equidigital number, since it uses as much as digits as its factorization.

42784921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 32256, while the sum is 37.

The square root of 42784921 is about 6541.0183457930. The cubic root of 42784921 is about 349.7547152161.

The spelling of 42784921 in words is "forty-two million, seven hundred eighty-four thousand, nine hundred twenty-one".