21121754 has 8 divisors (see below), whose sum is σ = 31703508. Its totient is φ = 10553920.

The previous prime is 21121741. The next prime is 21121759. The reversal of 21121754 is 45712112.

It can be written as a sum of positive squares in 2 ways, for example, as 20457529 + 664225 = 4523^2 + 815^2 .

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

It is a super-2 number, since 2×21121754² = 892256984073032, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21121759) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2114 + ... + 6834.

Almost surely, 2^21121754 is an apocalyptic number.

21121754 is a deficient number, since it is larger than the sum of its proper divisors (10581754).

21121754 is a wasteful number, since it uses less digits than its factorization.

21121754 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6960.

The product of its digits is 560, while the sum is 23.

The square root of 21121754 is about 4595.8409458988. The cubic root of 21121754 is about 276.4245810608.

Adding to 21121754 its reverse (45712112), we get a palindrome (66833866).

The spelling of 21121754 in words is "twenty-one million, one hundred twenty-one thousand, seven hundred fifty-four".