42507721 has 2 divisors, whose sum is σ = 42507722. Its totient is φ = 42507720.

The previous prime is 42507697. The next prime is 42507737. The reversal of 42507721 is 12770524.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26419600 + 16088121 = 5140^2 + 4011^2 .

It is a cyclic number.

It is not a de Polignac number, because 42507721 - 2¹⁵ = 42474953 is a prime.

It is a super-2 number, since 2×42507721² = 3613812689227682, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 42507721.

It is not a weakly prime, because it can be changed into another prime (42507121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21253860 + 21253861.

It is an arithmetic number, because the mean of its divisors is an integer number (21253861).

Almost surely, 2^42507721 is an apocalyptic number.

It is an amenable number.

42507721 is a deficient number, since it is larger than the sum of its proper divisors (1).

42507721 is an equidigital number, since it uses as much as digits as its factorization.

42507721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3920, while the sum is 28.

The square root of 42507721 is about 6519.7945519778. The cubic root of 42507721 is about 348.9977339940.

The spelling of 42507721 in words is "forty-two million, five hundred seven thousand, seven hundred twenty-one".