21402042 has 8 divisors (see below), whose sum is σ = 42804096. Its totient is φ = 7134012.

The previous prime is 21402023. The next prime is 21402047. The reversal of 21402042 is 24020412.

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

21402042 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (21402047) 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, 1783498 + ... + 1783509.

It is an arithmetic number, because the mean of its divisors is an integer number (5350512).

Almost surely, 2^21402042 is an apocalyptic number.

21402042 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21402042 is a wasteful number, since it uses less digits than its factorization.

21402042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3567012.

The product of its (nonzero) digits is 128, while the sum is 15.

The square root of 21402042 is about 4626.2341056198. The cubic root of 21402042 is about 277.6419402094.

Adding to 21402042 its reverse (24020412), we get a palindrome (45422454).

The spelling of 21402042 in words is "twenty-one million, four hundred two thousand, forty-two".