21457810 has 16 divisors (see below), whose sum is σ = 42135552. Its totient is φ = 7802800.

The previous prime is 21457771. The next prime is 21457819. The reversal of 21457810 is 1875412.

It is a super-2 number, since 2×21457810² = 920875219992200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21457819) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 97426 + ... + 97645.

It is an arithmetic number, because the mean of its divisors is an integer number (2633472).

Almost surely, 2^21457810 is an apocalyptic number.

21457810 is a deficient number, since it is larger than the sum of its proper divisors (20677742).

21457810 is a wasteful number, since it uses less digits than its factorization.

21457810 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 195089.

The product of its (nonzero) digits is 2240, while the sum is 28.

The square root of 21457810 is about 4632.2575489711. The cubic root of 21457810 is about 277.8828846094.

The spelling of 21457810 in words is "twenty-one million, four hundred fifty-seven thousand, eight hundred ten".