21787532 has 24 divisors (see below), whose sum is σ = 42848736. Its totient is φ = 9618048.

The previous prime is 21787531. The next prime is 21787543. The reversal of 21787532 is 23578712.

It is a junction number, because it is equal to n+sod(n) for n = 21787492 and 21787501.

It is not an unprimeable number, because it can be changed into a prime (21787531) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7913 + ... + 10304.

It is an arithmetic number, because the mean of its divisors is an integer number (1785364).

Almost surely, 2^21787532 is an apocalyptic number.

It is an amenable number.

21787532 is a deficient number, since it is larger than the sum of its proper divisors (21061204).

21787532 is a wasteful number, since it uses less digits than its factorization.

21787532 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18257 (or 18255 counting only the distinct ones).

The product of its digits is 23520, while the sum is 35.

The square root of 21787532 is about 4667.7116449070. The cubic root of 21787532 is about 279.2989776417.

The spelling of 21787532 in words is "twenty-one million, seven hundred eighty-seven thousand, five hundred thirty-two".