20616551 has 4 divisors (see below), whose sum is σ = 20877600. Its totient is φ = 20355504.

The previous prime is 20616521. The next prime is 20616559. The reversal of 20616551 is 15561602.

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

It is a cyclic number.

It is not a de Polignac number, because 20616551 - 2²² = 16422247 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20616551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20616559) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 130406 + ... + 130563.

It is an arithmetic number, because the mean of its divisors is an integer number (5219400).

Almost surely, 2^20616551 is an apocalyptic number.

20616551 is a deficient number, since it is larger than the sum of its proper divisors (261049).

20616551 is an equidigital number, since it uses as much as digits as its factorization.

20616551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 261048.

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 20616551 is about 4540.5452315774. The cubic root of 20616551 is about 274.2028751288.

The spelling of 20616551 in words is "twenty million, six hundred sixteen thousand, five hundred fifty-one".