42121621 has 2 divisors, whose sum is σ = 42121622. Its totient is φ = 42121620.

The previous prime is 42121603. The next prime is 42121643. The reversal of 42121621 is 12612124.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42120100 + 1521 = 6490^2 + 39^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-42121621 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42121661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21060810 + 21060811.

It is an arithmetic number, because the mean of its divisors is an integer number (21060811).

Almost surely, 2^42121621 is an apocalyptic number.

It is an amenable number.

42121621 is a deficient number, since it is larger than the sum of its proper divisors (1).

42121621 is an equidigital number, since it uses as much as digits as its factorization.

42121621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 192, while the sum is 19.

The square root of 42121621 is about 6490.1171792195. The cubic root of 42121621 is about 347.9378632398.

Adding to 42121621 its reverse (12612124), we get a palindrome (54733745).

The spelling of 42121621 in words is "forty-two million, one hundred twenty-one thousand, six hundred twenty-one".