21121351 has 4 divisors (see below), whose sum is σ = 21479400. Its totient is φ = 20763304.

The previous prime is 21121349. The next prime is 21121363. The reversal of 21121351 is 15312112.

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

It is a cyclic number.

It is not a de Polignac number, because 21121351 - 2¹ = 21121349 is a prime.

It is a super-2 number, since 2×21121351² = 892222936130402, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121381) 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, 178936 + ... + 179053.

It is an arithmetic number, because the mean of its divisors is an integer number (5369850).

Almost surely, 2^21121351 is an apocalyptic number.

21121351 is a deficient number, since it is larger than the sum of its proper divisors (358049).

21121351 is an equidigital number, since it uses as much as digits as its factorization.

21121351 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 358048.

The product of its digits is 60, while the sum is 16.

The square root of 21121351 is about 4595.7971017006. The cubic root of 21121351 is about 276.4228230027.

Adding to 21121351 its reverse (15312112), we get a palindrome (36433463).

The spelling of 21121351 in words is "twenty-one million, one hundred twenty-one thousand, three hundred fifty-one".