1639425994 has 4 divisors (see below), whose sum is σ = 2459138994. Its totient is φ = 819712996.

The previous prime is 1639425967. The next prime is 1639426021. The reversal of 1639425994 is 4995249361.

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

It is an interprime number because it is at equal distance from previous prime (1639425967) and next prime (1639426021).

It can be written as a sum of positive squares in only one way, i.e., 1268285769 + 371140225 = 35613^2 + 19265^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 409856497 + ... + 409856500.

Almost surely, 2^1639425994 is an apocalyptic number.

1639425994 is a deficient number, since it is larger than the sum of its proper divisors (819713000).

1639425994 is an equidigital number, since it uses as much as digits as its factorization.

1639425994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 819712999.

The product of its digits is 2099520, while the sum is 52.

The square root of 1639425994 is about 40489.8258084670. The cubic root of 1639425994 is about 1179.1361085687.

The spelling of 1639425994 in words is "one billion, six hundred thirty-nine million, four hundred twenty-five thousand, nine hundred ninety-four".