20642555 has 4 divisors (see below), whose sum is σ = 24771072. Its totient is φ = 16514040.

The previous prime is 20642527. The next prime is 20642561. The reversal of 20642555 is 55524602.

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

It is not a de Polignac number, because 20642555 - 2⁸ = 20642299 is a prime.

It is a super-2 number, since 2×20642555² = 852230153856050, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2064251 + ... + 2064260.

It is an arithmetic number, because the mean of its divisors is an integer number (6192768).

Almost surely, 2^20642555 is an apocalyptic number.

20642555 is a deficient number, since it is larger than the sum of its proper divisors (4128517).

20642555 is an equidigital number, since it uses as much as digits as its factorization.

20642555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4128516.

The product of its (nonzero) digits is 12000, while the sum is 29.

The square root of 20642555 is about 4543.4078619468. The cubic root of 20642555 is about 274.3181122471.

The spelling of 20642555 in words is "twenty million, six hundred forty-two thousand, five hundred fifty-five".