421205551 has 4 divisors (see below), whose sum is σ = 453605992. Its totient is φ = 388805112.

The previous prime is 421205527. The next prime is 421205569. The reversal of 421205551 is 155502124.

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 421205551 - 2¹⁵ = 421172783 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (421205951) 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, 16200201 + ... + 16200226.

It is an arithmetic number, because the mean of its divisors is an integer number (113401498).

Almost surely, 2^421205551 is an apocalyptic number.

421205551 is a deficient number, since it is larger than the sum of its proper divisors (32400441).

421205551 is a wasteful number, since it uses less digits than its factorization.

421205551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32400440.

The product of its (nonzero) digits is 2000, while the sum is 25.

The square root of 421205551 is about 20523.2928888129. The cubic root of 421205551 is about 749.6030794573.

Adding to 421205551 its reverse (155502124), we get a palindrome (576707675).

The spelling of 421205551 in words is "four hundred twenty-one million, two hundred five thousand, five hundred fifty-one".