840072257 has 8 divisors (see below), whose sum is σ = 848476200. Its totient is φ = 831709440.

The previous prime is 840072253. The next prime is 840072269. The reversal of 840072257 is 752270048.

It is a Cunningham number, because it is equal to 28984²+1.

It can be written as a sum of positive squares in 4 ways, for example, as 385572496 + 454499761 = 19636^2 + 21319^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 840072257 - 2² = 840072253 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (840072253) 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, 31619 + ... + 51767.

It is an arithmetic number, because the mean of its divisors is an integer number (106059525).

Almost surely, 2^840072257 is an apocalyptic number.

It is an amenable number.

840072257 is a deficient number, since it is larger than the sum of its proper divisors (8403943).

840072257 is a wasteful number, since it uses less digits than its factorization.

840072257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20563.

The product of its (nonzero) digits is 31360, while the sum is 35.

The square root of 840072257 is about 28984.0000172509. Note that the first 4 decimals coincide. The cubic root of 840072257 is about 943.5658497649.

The spelling of 840072257 in words is "eight hundred forty million, seventy-two thousand, two hundred fifty-seven".