21213554 has 8 divisors (see below), whose sum is σ = 32223360. Its totient is φ = 10472436.

The previous prime is 21213553. The next prime is 21213559. The reversal of 21213554 is 45531212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21213553) 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, 66974 + ... + 67289.

It is an arithmetic number, because the mean of its divisors is an integer number (4027920).

Almost surely, 2^21213554 is an apocalyptic number.

21213554 is a deficient number, since it is larger than the sum of its proper divisors (11009806).

21213554 is a wasteful number, since it uses less digits than its factorization.

21213554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134344.

The product of its digits is 1200, while the sum is 23.

The square root of 21213554 is about 4605.8174084521. The cubic root of 21213554 is about 276.8244705470.

Adding to 21213554 its reverse (45531212), we get a palindrome (66744766).

The spelling of 21213554 in words is "twenty-one million, two hundred thirteen thousand, five hundred fifty-four".