21357442 has 8 divisors (see below), whose sum is σ = 32561532. Its totient is φ = 10503600.

The previous prime is 21357431. The next prime is 21357443. The reversal of 21357442 is 24475312.

It can be written as a sum of positive squares in 2 ways, for example, as 13623481 + 7733961 = 3691^2 + 2781^2 .

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

It is a super-2 number, since 2×21357442² = 912280657566728, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21357442.

It is not an unprimeable number, because it can be changed into a prime (21357443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 87409 + ... + 87652.

Almost surely, 2^21357442 is an apocalyptic number.

21357442 is a deficient number, since it is larger than the sum of its proper divisors (11204090).

21357442 is a wasteful number, since it uses less digits than its factorization.

21357442 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175124.

The product of its digits is 6720, while the sum is 28.

The square root of 21357442 is about 4621.4112563155. The cubic root of 21357442 is about 277.4489455084.

The spelling of 21357442 in words is "twenty-one million, three hundred fifty-seven thousand, four hundred forty-two".