21121743 has 8 divisors (see below), whose sum is σ = 28325808. Its totient is φ = 13999424.

The previous prime is 21121741. The next prime is 21121759. The reversal of 21121743 is 34712112.

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

It is a cyclic number.

It is not a de Polignac number, because 21121743 - 2¹ = 21121741 is a prime.

It is a super-2 number, since 2×21121743² = 892256054716098, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121741) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19830 + ... + 20867.

It is an arithmetic number, because the mean of its divisors is an integer number (3540726).

Almost surely, 2^21121743 is an apocalyptic number.

21121743 is a deficient number, since it is larger than the sum of its proper divisors (7204065).

21121743 is a wasteful number, since it uses less digits than its factorization.

21121743 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40873.

The product of its digits is 336, while the sum is 21.

The square root of 21121743 is about 4595.8397491645. The cubic root of 21121743 is about 276.4245330744.

Adding to 21121743 its reverse (34712112), we get a palindrome (55833855).

The spelling of 21121743 in words is "twenty-one million, one hundred twenty-one thousand, seven hundred forty-three".