21434551 has 6 divisors (see below), whose sum is σ = 22407560. Its totient is φ = 20502108.

The previous prime is 21434531. The next prime is 21434579. The reversal of 21434551 is 15543412.

21434551 = 523² + 524² + ... + 591².

It is a happy number.

It is not a de Polignac number, because 21434551 - 2¹³ = 21426359 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 (21434531) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 19731 + ... + 20788.

Almost surely, 2^21434551 is an apocalyptic number.

21434551 is a deficient number, since it is larger than the sum of its proper divisors (973009).

21434551 is an equidigital number, since it uses as much as digits as its factorization.

21434551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40565 (or 40542 counting only the distinct ones).

The product of its digits is 2400, while the sum is 25.

The square root of 21434551 is about 4629.7463213442. The cubic root of 21434551 is about 277.7824454268.

Adding to 21434551 its reverse (15543412), we get a palindrome (36977963).

The spelling of 21434551 in words is "twenty-one million, four hundred thirty-four thousand, five hundred fifty-one".