1625138778 has 8 divisors (see below), whose sum is σ = 3250277568. Its totient is φ = 541712924.

The previous prime is 1625138773. The next prime is 1625138789. The reversal of 1625138778 is 8778315261.

It is a happy number.

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

1625138778 is an admirable number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1625138773) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 135428226 + ... + 135428237.

It is an arithmetic number, because the mean of its divisors is an integer number (406284696).

Almost surely, 2^1625138778 is an apocalyptic number.

1625138778 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

1625138778 is a wasteful number, since it uses less digits than its factorization.

1625138778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 270856468.

The product of its digits is 564480, while the sum is 48.

The square root of 1625138778 is about 40313.0100339828. The cubic root of 1625138778 is about 1175.7008109616.

The spelling of 1625138778 in words is "one billion, six hundred twenty-five million, one hundred thirty-eight thousand, seven hundred seventy-eight".