2516540021 has 2 divisors, whose sum is σ = 2516540022. Its totient is φ = 2516540020.

The previous prime is 2516539973. The next prime is 2516540053. The reversal of 2516540021 is 1200456152.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1734722500 + 781817521 = 41650^2 + 27961^2 .

It is a cyclic number.

It is not a de Polignac number, because 2516540021 - 2⁶ = 2516539957 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2516543021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1258270010 + 1258270011.

It is an arithmetic number, because the mean of its divisors is an integer number (1258270011).

Almost surely, 2^2516540021 is an apocalyptic number.

It is an amenable number.

2516540021 is a deficient number, since it is larger than the sum of its proper divisors (1).

2516540021 is an equidigital number, since it uses as much as digits as its factorization.

2516540021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2400, while the sum is 26.

The square root of 2516540021 is about 50165.1275389588. The cubic root of 2516540021 is about 1360.1953332828.

Adding to 2516540021 its reverse (1200456152), we get a palindrome (3716996173).

The spelling of 2516540021 in words is "two billion, five hundred sixteen million, five hundred forty thousand, twenty-one".