21917142 has 48 divisors (see below), whose sum is σ = 53049360. Its totient is φ = 6741792.

The previous prime is 21917113. The next prime is 21917149. The reversal of 21917142 is 24171912.

It is a super-2 number, since 2×21917142² = 960722226896328, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21917149) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4584 + ... + 8052.

It is an arithmetic number, because the mean of its divisors is an integer number (1105195).

Almost surely, 2^21917142 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21917142, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26524680).

21917142 is an abundant number, since it is smaller than the sum of its proper divisors (31132218).

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

21917142 is a wasteful number, since it uses less digits than its factorization.

21917142 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3499 (or 3487 counting only the distinct ones).

The product of its digits is 1008, while the sum is 27.

The square root of 21917142 is about 4681.5747350651. The cubic root of 21917142 is about 279.8517157021.

The spelling of 21917142 in words is "twenty-one million, nine hundred seventeen thousand, one hundred forty-two".