21829457 has 4 divisors (see below), whose sum is σ = 23508660. Its totient is φ = 20150256.

The previous prime is 21829439. The next prime is 21829463. The reversal of 21829457 is 75492812.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1615441 + 20214016 = 1271^2 + 4496^2 .

It is a cyclic number.

It is not a de Polignac number, because 21829457 - 2¹² = 21825361 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21829457.

It is not an unprimeable number, because it can be changed into a prime (21829477) 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, 839582 + ... + 839607.

It is an arithmetic number, because the mean of its divisors is an integer number (5877165).

Almost surely, 2^21829457 is an apocalyptic number.

It is an amenable number.

21829457 is a deficient number, since it is larger than the sum of its proper divisors (1679203).

21829457 is a wasteful number, since it uses less digits than its factorization.

21829457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1679202.

The product of its digits is 40320, while the sum is 38.

The square root of 21829457 is about 4672.2004451864. The cubic root of 21829457 is about 279.4780113334.

The spelling of 21829457 in words is "twenty-one million, eight hundred twenty-nine thousand, four hundred fifty-seven".