2078781521 has 4 divisors (see below), whose sum is σ = 2079202032. Its totient is φ = 2078361012.

The previous prime is 2078781503. The next prime is 2078781527. The reversal of 2078781521 is 1251878702.

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 2078781521 - 2²² = 2074587217 is a prime.

It is a super-2 number, since 2×2078781521² = 8642665224102146882, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2078781527) 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, 202751 + ... + 212756.

It is an arithmetic number, because the mean of its divisors is an integer number (519800508).

Almost surely, 2^2078781521 is an apocalyptic number.

It is an amenable number.

2078781521 is a deficient number, since it is larger than the sum of its proper divisors (420511).

2078781521 is an equidigital number, since it uses as much as digits as its factorization.

2078781521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 420510.

The product of its (nonzero) digits is 62720, while the sum is 41.

The square root of 2078781521 is about 45593.6565872929. The cubic root of 2078781521 is about 1276.2515499467.

The spelling of 2078781521 in words is "two billion, seventy-eight million, seven hundred eighty-one thousand, five hundred twenty-one".