291297640 has 32 divisors (see below), whose sum is σ = 657515880. Its totient is φ = 116146432.

The previous prime is 291297583. The next prime is 291297641. The reversal of 291297640 is 46792192.

It can be written as a sum of positive squares in 4 ways, for example, as 169989444 + 121308196 = 13038^2 + 11014^2 .

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 291297593 and 291297602.

It is not an unprimeable number, because it can be changed into a prime (291297641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1194 + ... + 24166.

Almost surely, 2^291297640 is an apocalyptic number.

291297640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

291297640 is an abundant number, since it is smaller than the sum of its proper divisors (366218240).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

291297640 is a wasteful number, since it uses less digits than its factorization.

291297640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23301 (or 23297 counting only the distinct ones).

The product of its (nonzero) digits is 54432, while the sum is 40.

The square root of 291297640 is about 17067.4438625120. The cubic root of 291297640 is about 662.8963921857.

The spelling of 291297640 in words is "two hundred ninety-one million, two hundred ninety-seven thousand, six hundred forty".