21438534 has 16 divisors (see below), whose sum is σ = 46175472. Its totient is φ = 6596448.

The previous prime is 21438499. The next prime is 21438541. The reversal of 21438534 is 43583412.

It is a super-2 number, since 2×21438534² = 919221480138312, which contains 22 as substring.

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, 137349 + ... + 137504.

It is an arithmetic number, because the mean of its divisors is an integer number (2885967).

Almost surely, 2^21438534 is an apocalyptic number.

21438534 is an abundant number, since it is smaller than the sum of its proper divisors (24736938).

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

21438534 is a wasteful number, since it uses less digits than its factorization.

21438534 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 274871.

The product of its digits is 11520, while the sum is 30.

The square root of 21438534 is about 4630.1764545209. The cubic root of 21438534 is about 277.7996503429.

The spelling of 21438534 in words is "twenty-one million, four hundred thirty-eight thousand, five hundred thirty-four".