690248781 has 6 divisors (see below), whose sum is σ = 997026030. Its totient is φ = 460165848.

The previous prime is 690248747. The next prime is 690248789. The reversal of 690248781 is 187842096.

690248781 is a `hidden beast` number, since 6 + 90 + 2 + 487 + 81 = 666.

It can be written as a sum of positive squares in only one way, i.e., 458174025 + 232074756 = 21405^2 + 15234^2 .

It is not a de Polignac number, because 690248781 - 2⁶ = 690248717 is a prime.

It is a super-2 number, since 2×690248781² = 952886759343971922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (690248789) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 38347146 + ... + 38347163.

It is an arithmetic number, because the mean of its divisors is an integer number (166171005).

Almost surely, 2^690248781 is an apocalyptic number.

It is an amenable number.

690248781 is a deficient number, since it is larger than the sum of its proper divisors (306777249).

690248781 is a wasteful number, since it uses less digits than its factorization.

690248781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76694315 (or 76694312 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 45.

The square root of 690248781 is about 26272.5861117630. The cubic root of 690248781 is about 883.7617807941.

The spelling of 690248781 in words is "six hundred ninety million, two hundred forty-eight thousand, seven hundred eighty-one".