1997685251 has 8 divisors (see below), whose sum is σ = 2128163520. Its totient is φ = 1869740712.

The previous prime is 1997685247. The next prime is 1997685257. The reversal of 1997685251 is 1525867991.

It is a happy number.

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 1997685251 - 2² = 1997685247 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1997685193 and 1997685202.

It is not an unprimeable number, because it can be changed into a prime (1997685257) 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, 631805 + ... + 634958.

It is an arithmetic number, because the mean of its divisors is an integer number (266020440).

Almost surely, 2^1997685251 is an apocalyptic number.

1997685251 is a deficient number, since it is larger than the sum of its proper divisors (130478269).

1997685251 is a wasteful number, since it uses less digits than its factorization.

1997685251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1266865.

The product of its digits is 1360800, while the sum is 53.

The square root of 1997685251 is about 44695.4723769645. The cubic root of 1997685251 is about 1259.4347954220.

The spelling of 1997685251 in words is "one billion, nine hundred ninety-seven million, six hundred eighty-five thousand, two hundred fifty-one".