781642 has 4 divisors (see below), whose sum is σ = 1172466. Its totient is φ = 390820.

The previous prime is 781633. The next prime is 781661. The reversal of 781642 is 246187.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 408321 + 373321 = 639^2 + 611^2 .

It is a super-2 number, since 2×781642² = 1221928432328, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 781642.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195409 + ... + 195412.

2⁷⁸¹⁶⁴² is an apocalyptic number.

781642 is a deficient number, since it is larger than the sum of its proper divisors (390824).

781642 is a wasteful number, since it uses less digits than its factorization.

781642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 390823.

The product of its digits is 2688, while the sum is 28.

The square root of 781642 is about 884.1051973606. The cubic root of 781642 is about 92.1161890540.

The spelling of 781642 in words is "seven hundred eighty-one thousand, six hundred forty-two".