42897721 has 2 divisors, whose sum is σ = 42897722. Its totient is φ = 42897720.

The previous prime is 42897683. The next prime is 42897727. The reversal of 42897721 is 12779824.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 36772096 + 6125625 = 6064^2 + 2475^2 .

It is a cyclic number.

It is not a de Polignac number, because 42897721 - 2¹³ = 42889529 is a prime.

It is not a weakly prime, because it can be changed into another prime (42897727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21448860 + 21448861.

It is an arithmetic number, because the mean of its divisors is an integer number (21448861).

Almost surely, 2^42897721 is an apocalyptic number.

It is an amenable number.

42897721 is a deficient number, since it is larger than the sum of its proper divisors (1).

42897721 is an equidigital number, since it uses as much as digits as its factorization.

42897721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 56448, while the sum is 40.

The square root of 42897721 is about 6549.6351806799. The cubic root of 42897721 is about 350.0618149323.

The spelling of 42897721 in words is "forty-two million, eight hundred ninety-seven thousand, seven hundred twenty-one".