2021721587 has 2 divisors, whose sum is σ = 2021721588. Its totient is φ = 2021721586.

The previous prime is 2021721571. The next prime is 2021721593. The reversal of 2021721587 is 7851271202.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2021721587 - 2⁴ = 2021721571 is a prime.

It is not a weakly prime, because it can be changed into another prime (2021721557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1010860793 + 1010860794.

It is an arithmetic number, because the mean of its divisors is an integer number (1010860794).

Almost surely, 2^2021721587 is an apocalyptic number.

2021721587 is a deficient number, since it is larger than the sum of its proper divisors (1).

2021721587 is an equidigital number, since it uses as much as digits as its factorization.

2021721587 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15680, while the sum is 35.

The square root of 2021721587 is about 44963.5584334692. The cubic root of 2021721587 is about 1264.4658833419.

Adding to 2021721587 its reverse (7851271202), we get a palindrome (9872992789).

The spelling of 2021721587 in words is "two billion, twenty-one million, seven hundred twenty-one thousand, five hundred eighty-seven".