20945642 has 4 divisors (see below), whose sum is σ = 31418466. Its totient is φ = 10472820.

The previous prime is 20945623. The next prime is 20945651. The reversal of 20945642 is 24654902.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 24654902 = 2 ⋅12327451.

It can be written as a sum of positive squares in only one way, i.e., 19882681 + 1062961 = 4459^2 + 1031^2 .

It is a junction number, because it is equal to n+sod(n) for n = 20945599 and 20945608.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5236409 + ... + 5236412.

Almost surely, 2^20945642 is an apocalyptic number.

20945642 is a deficient number, since it is larger than the sum of its proper divisors (10472824).

20945642 is a wasteful number, since it uses less digits than its factorization.

20945642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10472823.

The product of its (nonzero) digits is 17280, while the sum is 32.

The square root of 20945642 is about 4576.6409079149. The cubic root of 20945642 is about 275.6541649645.

The spelling of 20945642 in words is "twenty million, nine hundred forty-five thousand, six hundred forty-two".