21154471 has 4 divisors (see below), whose sum is σ = 22781752. Its totient is φ = 19527192.

The previous prime is 21154447. The next prime is 21154487. The reversal of 21154471 is 17445112.

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 21154471 - 2⁹ = 21153959 is a prime.

It is a super-3 number, since 3×21154471³ (a number of 23 digits) contains 333 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 (21158471) 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, 813621 + ... + 813646.

It is an arithmetic number, because the mean of its divisors is an integer number (5695438).

Almost surely, 2^21154471 is an apocalyptic number.

21154471 is a deficient number, since it is larger than the sum of its proper divisors (1627281).

21154471 is a wasteful number, since it uses less digits than its factorization.

21154471 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1627280.

The product of its digits is 1120, while the sum is 25.

The square root of 21154471 is about 4599.3989824759. The cubic root of 21154471 is about 276.5672320533.

Adding to 21154471 its reverse (17445112), we get a palindrome (38599583).

The spelling of 21154471 in words is "twenty-one million, one hundred fifty-four thousand, four hundred seventy-one".