21864546 has 32 divisors (see below), whose sum is σ = 53006400. Its totient is φ = 6625440.

The previous prime is 21864529. The next prime is 21864547. The reversal of 21864546 is 64546812.

21864546 is a `hidden beast` number, since 2 + 1 + 8 + 645 + 4 + 6 = 666.

It is a super-2 number, since 2×21864546² = 956116743572232, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21864546.

It is not an unprimeable number, because it can be changed into a prime (21864547) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17811 + ... + 18998.

It is an arithmetic number, because the mean of its divisors is an integer number (1656450).

Almost surely, 2^21864546 is an apocalyptic number.

21864546 is an abundant number, since it is smaller than the sum of its proper divisors (31141854).

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

21864546 is a wasteful number, since it uses less digits than its factorization.

21864546 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36831 (or 36825 counting only the distinct ones).

The product of its digits is 46080, while the sum is 36.

The square root of 21864546 is about 4675.9540203043. The cubic root of 21864546 is about 279.6276769007.

The spelling of 21864546 in words is "twenty-one million, eight hundred sixty-four thousand, five hundred forty-six".