1256620642 has 4 divisors (see below), whose sum is σ = 1884930966. Its totient is φ = 628310320.

The previous prime is 1256620639. The next prime is 1256620643. The reversal of 1256620642 is 2460266521.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 2460266521 = 2069 ⋅1189109.

It can be written as a sum of positive squares in only one way, i.e., 901260441 + 355360201 = 30021^2 + 18851^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1256620598 and 1256620607.

It is not an unprimeable number, because it can be changed into a prime (1256620643) 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 as a sum of consecutive naturals, namely, 314155159 + ... + 314155162.

Almost surely, 2^1256620642 is an apocalyptic number.

1256620642 is a deficient number, since it is larger than the sum of its proper divisors (628310324).

1256620642 is an equidigital number, since it uses as much as digits as its factorization.

1256620642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 628310323.

The product of its (nonzero) digits is 34560, while the sum is 34.

The square root of 1256620642 is about 35448.8454254860. The cubic root of 1256620642 is about 1079.1158292740.

The spelling of 1256620642 in words is "one billion, two hundred fifty-six million, six hundred twenty thousand, six hundred forty-two".