20642999 has 4 divisors (see below), whose sum is σ = 22230936. Its totient is φ = 19055064.

The previous prime is 20642971. The next prime is 20643043. The reversal of 20642999 is 99924602.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20642999 is a prime.

It is a super-2 number, since 2×20642999² = 852266815428002, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20642099) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 793949 + ... + 793974.

It is an arithmetic number, because the mean of its divisors is an integer number (5557734).

Almost surely, 2^20642999 is an apocalyptic number.

20642999 is a deficient number, since it is larger than the sum of its proper divisors (1587937).

20642999 is a wasteful number, since it uses less digits than its factorization.

20642999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1587936.

The product of its (nonzero) digits is 69984, while the sum is 41.

The square root of 20642999 is about 4543.4567236852. The cubic root of 20642999 is about 274.3200789992.

The spelling of 20642999 in words is "twenty million, six hundred forty-two thousand, nine hundred ninety-nine".