21021451 has 12 divisors (see below), whose sum is σ = 23460136. Its totient is φ = 18817920.

The previous prime is 21021449. The next prime is 21021457. The reversal of 21021451 is 15412012.

It is not a de Polignac number, because 21021451 - 2¹ = 21021449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21021457) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6811 + ... + 9403.

Almost surely, 2^21021451 is an apocalyptic number.

21021451 is a deficient number, since it is larger than the sum of its proper divisors (2438685).

21021451 is a wasteful number, since it uses less digits than its factorization.

21021451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2682 (or 2671 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 21021451 is about 4584.9155935524. The cubic root of 21021451 is about 275.9863248493.

Adding to 21021451 its reverse (15412012), we get a palindrome (36433463).

It can be divided in two parts, 2102 and 1451, that added together give a palindrome (3553).

The spelling of 21021451 in words is "twenty-one million, twenty-one thousand, four hundred fifty-one".