21084542 has 4 divisors (see below), whose sum is σ = 31626816. Its totient is φ = 10542270.

The previous prime is 21084541. The next prime is 21084551. The reversal of 21084542 is 24548012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a super-2 number, since 2×21084542² = 889115822699528, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21084541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5271134 + ... + 5271137.

It is an arithmetic number, because the mean of its divisors is an integer number (7906704).

Almost surely, 2^21084542 is an apocalyptic number.

21084542 is a deficient number, since it is larger than the sum of its proper divisors (10542274).

21084542 is a wasteful number, since it uses less digits than its factorization.

21084542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10542273.

The product of its (nonzero) digits is 2560, while the sum is 26.

The square root of 21084542 is about 4591.7907182275. The cubic root of 21084542 is about 276.2621520285.

The spelling of 21084542 in words is "twenty-one million, eighty-four thousand, five hundred forty-two".