21506268 has 48 divisors (see below), whose sum is σ = 57576960. Its totient is φ = 6120384.

The previous prime is 21506257. The next prime is 21506269. The reversal of 21506268 is 86260512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21506269) 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, 41998 + ... + 42506.

It is an arithmetic number, because the mean of its divisors is an integer number (1199520).

Almost surely, 2^21506268 is an apocalyptic number.

21506268 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21506268 is an abundant number, since it is smaller than the sum of its proper divisors (36070692).

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

21506268 is a wasteful number, since it uses less digits than its factorization.

21506268 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1026 (or 1024 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 30.

The square root of 21506268 is about 4637.4850943157. The cubic root of 21506268 is about 278.0919075722.

The spelling of 21506268 in words is "twenty-one million, five hundred six thousand, two hundred sixty-eight".