2781157778 has 12 divisors (see below), whose sum is σ = 4852836702. Its totient is φ = 1191924720.

The previous prime is 2781157763. The next prime is 2781157807. The reversal of 2781157778 is 8777511872.

It can be written as a sum of positive squares in only one way, i.e., 1775189689 + 1005968089 = 42133^2 + 31717^2 .

It is a super-2 number, since 2×2781157778² = 15469677172259794568, which contains 22 as substring.

It is a Smith number, since the sum of its digits (53) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 14189483 + ... + 14189678.

Almost surely, 2^2781157778 is an apocalyptic number.

2781157778 is a deficient number, since it is larger than the sum of its proper divisors (2071678924).

2781157778 is a wasteful number, since it uses less digits than its factorization.

2781157778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28379177 (or 28379170 counting only the distinct ones).

The product of its digits is 1536640, while the sum is 53.

The square root of 2781157778 is about 52736.6834186603. The cubic root of 2781157778 is about 1406.2910382546.

The spelling of 2781157778 in words is "two billion, seven hundred eighty-one million, one hundred fifty-seven thousand, seven hundred seventy-eight".