21801442 has 8 divisors (see below), whose sum is σ = 35217756. Its totient is φ = 10062192.

The previous prime is 21801433. The next prime is 21801443. The reversal of 21801442 is 24410812.

It can be written as a sum of positive squares in 2 ways, for example, as 15139881 + 6661561 = 3891^2 + 2581^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21801443) 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, 419233 + ... + 419284.

Almost surely, 2^21801442 is an apocalyptic number.

21801442 is a deficient number, since it is larger than the sum of its proper divisors (13416314).

21801442 is a wasteful number, since it uses less digits than its factorization.

21801442 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 838532.

The product of its (nonzero) digits is 512, while the sum is 22.

The square root of 21801442 is about 4669.2014306517. The cubic root of 21801442 is about 279.3584034069.

The spelling of 21801442 in words is "twenty-one million, eight hundred one thousand, four hundred forty-two".