2521231781 has 4 divisors (see below), whose sum is σ = 2521451232. Its totient is φ = 2521012332.

The previous prime is 2521231759. The next prime is 2521231861. The reversal of 2521231781 is 1871321252.

2521231781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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.

It is a cyclic number.

It is not a de Polignac number, because 2521231781 - 2²² = 2517037477 is a prime.

It is a super-2 number, since 2×2521231781² = 12713219387048863922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2521231751) 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, 91481 + ... + 115806.

It is an arithmetic number, because the mean of its divisors is an integer number (630362808).

Almost surely, 2^2521231781 is an apocalyptic number.

It is an amenable number.

2521231781 is a deficient number, since it is larger than the sum of its proper divisors (219451).

2521231781 is a wasteful number, since it uses less digits than its factorization.

2521231781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 219450.

The product of its digits is 6720, while the sum is 32.

The square root of 2521231781 is about 50211.8689255837. The cubic root of 2521231781 is about 1361.0401106559.

The spelling of 2521231781 in words is "two billion, five hundred twenty-one million, two hundred thirty-one thousand, seven hundred eighty-one".