20278642 has 4 divisors (see below), whose sum is σ = 30417966. Its totient is φ = 10139320.

The previous prime is 20278631. The next prime is 20278649. The reversal of 20278642 is 24687202.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 24687202 = 2 ⋅12343601.

It can be written as a sum of positive squares in only one way, i.e., 20169081 + 109561 = 4491^2 + 331^2 .

It is a super-2 number, since 2×20278642² = 822446642728328, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20278649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5069659 + ... + 5069662.

Almost surely, 2^20278642 is an apocalyptic number.

20278642 is a deficient number, since it is larger than the sum of its proper divisors (10139324).

20278642 is a wasteful number, since it uses less digits than its factorization.

20278642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10139323.

The product of its (nonzero) digits is 10752, while the sum is 31.

The square root of 20278642 is about 4503.1813199115. The cubic root of 20278642 is about 272.6965369470.

The spelling of 20278642 in words is "twenty million, two hundred seventy-eight thousand, six hundred forty-two".