21131457 has 8 divisors (see below), whose sum is σ = 29400384. Its totient is φ = 13475088.

The previous prime is 21131449. The next prime is 21131489. The reversal of 21131457 is 75413112.

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

It is not a de Polignac number, because 21131457 - 2³ = 21131449 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21111457) 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, 153058 + ... + 153195.

It is an arithmetic number, because the mean of its divisors is an integer number (3675048).

Almost surely, 2^21131457 is an apocalyptic number.

It is an amenable number.

21131457 is a deficient number, since it is larger than the sum of its proper divisors (8268927).

21131457 is a wasteful number, since it uses less digits than its factorization.

21131457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 306279.

The product of its digits is 840, while the sum is 24.

The square root of 21131457 is about 4596.8964530431. The cubic root of 21131457 is about 276.4669029422.

Adding to 21131457 its reverse (75413112), we get a palindrome (96544569).

It can be divided in two parts, 2113 and 1457, that added together give a triangular number (3570 = T₈₄).

The spelling of 21131457 in words is "twenty-one million, one hundred thirty-one thousand, four hundred fifty-seven".