21154534 has 4 divisors (see below), whose sum is σ = 31731804. Its totient is φ = 10577266.

The previous prime is 21154519. The next prime is 21154547. The reversal of 21154534 is 43545112.

It is a happy number.

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

It is a junction number, because it is equal to n+sod(n) for n = 21154499 and 21154508.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5288632 + ... + 5288635.

It is an arithmetic number, because the mean of its divisors is an integer number (7932951).

Almost surely, 2^21154534 is an apocalyptic number.

21154534 is a deficient number, since it is larger than the sum of its proper divisors (10577270).

21154534 is a wasteful number, since it uses less digits than its factorization.

21154534 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10577269.

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

The square root of 21154534 is about 4599.4058311917. The cubic root of 21154534 is about 276.5675066007.

Adding to 21154534 its reverse (43545112), we get a palindrome (64699646).

It can be divided in two parts, 211 and 54534, that added together give a palindrome (54745).

The spelling of 21154534 in words is "twenty-one million, one hundred fifty-four thousand, five hundred thirty-four".