42639994 has 4 divisors (see below), whose sum is σ = 63959994. Its totient is φ = 21319996.

The previous prime is 42639991. The next prime is 42640001. The reversal of 42639994 is 49993624.

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., 33489369 + 9150625 = 5787^2 + 3025^2 .

It is not an unprimeable number, because it can be changed into a prime (42639991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10659997 + ... + 10660000.

Almost surely, 2^42639994 is an apocalyptic number.

42639994 is a deficient number, since it is larger than the sum of its proper divisors (21320000).

42639994 is a wasteful number, since it uses less digits than its factorization.

42639994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21319999.

The product of its digits is 419904, while the sum is 46.

The square root of 42639994 is about 6529.9306275029. The cubic root of 42639994 is about 349.3593559644.

The spelling of 42639994 in words is "forty-two million, six hundred thirty-nine thousand, nine hundred ninety-four".