21166542 has 32 divisors (see below), whose sum is σ = 47187360. Its totient is φ = 7032960.

The previous prime is 21166529. The next prime is 21166559. The reversal of 21166542 is 24566112.

21166542 is a `hidden beast` number, since 2 + 1 + 1 + 6 + 654 + 2 = 666.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31692 + ... + 32352.

It is an arithmetic number, because the mean of its divisors is an integer number (1474605).

Almost surely, 2^21166542 is an apocalyptic number.

21166542 is an abundant number, since it is smaller than the sum of its proper divisors (26020818).

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

21166542 is a wasteful number, since it uses less digits than its factorization.

21166542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1265 (or 1259 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 21166542 is about 4600.7110320036. The cubic root of 21166542 is about 276.6198262665.

The spelling of 21166542 in words is "twenty-one million, one hundred sixty-six thousand, five hundred forty-two".