21918542 has 16 divisors (see below), whose sum is σ = 35292672. Its totient is φ = 10172160.

The previous prime is 21918529. The next prime is 21918551. The reversal of 21918542 is 24581912.

It is a junction number, because it is equal to n+sod(n) for n = 21918499 and 21918508.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1934 + ... + 6897.

It is an arithmetic number, because the mean of its divisors is an integer number (2205792).

Almost surely, 2^21918542 is an apocalyptic number.

21918542 is a deficient number, since it is larger than the sum of its proper divisors (13374130).

21918542 is a wasteful number, since it uses less digits than its factorization.

21918542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8923.

The product of its digits is 5760, while the sum is 32.

The square root of 21918542 is about 4681.7242550155. The cubic root of 21918542 is about 279.8576742658.

The spelling of 21918542 in words is "twenty-one million, nine hundred eighteen thousand, five hundred forty-two".