21406354 has 4 divisors (see below), whose sum is σ = 32109534. Its totient is φ = 10703176.

The previous prime is 21406339. The next prime is 21406361. The reversal of 21406354 is 45360412.

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

It can be written as a sum of positive squares in only one way, i.e., 21372129 + 34225 = 4623^2 + 185^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5351587 + ... + 5351590.

Almost surely, 2^21406354 is an apocalyptic number.

21406354 is a deficient number, since it is larger than the sum of its proper divisors (10703180).

21406354 is a wasteful number, since it uses less digits than its factorization.

21406354 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10703179.

The product of its (nonzero) digits is 2880, while the sum is 25.

The square root of 21406354 is about 4626.7001199559. The cubic root of 21406354 is about 277.6605850292.

Adding to 21406354 its reverse (45360412), we get a palindrome (66766766).

The spelling of 21406354 in words is "twenty-one million, four hundred six thousand, three hundred fifty-four".