2021142581 has 4 divisors (see below), whose sum is σ = 2040031872. Its totient is φ = 2002253292.

The previous prime is 2021142577. The next prime is 2021142583. The reversal of 2021142581 is 1852411202.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1852411202 = 2 ⋅926205601.

It is a cyclic number.

It is not a de Polignac number, because 2021142581 - 2² = 2021142577 is a prime.

It is a super-2 number, since 2×2021142581² = 8170034665462683122, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2021142581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2021142583) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9444485 + ... + 9444698.

It is an arithmetic number, because the mean of its divisors is an integer number (510007968).

Almost surely, 2^2021142581 is an apocalyptic number.

It is an amenable number.

2021142581 is a deficient number, since it is larger than the sum of its proper divisors (18889291).

2021142581 is a wasteful number, since it uses less digits than its factorization.

2021142581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18889290.

The product of its (nonzero) digits is 1280, while the sum is 26.

The square root of 2021142581 is about 44957.1193583397. The cubic root of 2021142581 is about 1264.3451606137.

Adding to 2021142581 its reverse (1852411202), we get a palindrome (3873553783).

The spelling of 2021142581 in words is "two billion, twenty-one million, one hundred forty-two thousand, five hundred eighty-one".