21640146 has 16 divisors (see below), whose sum is σ = 47215008. Its totient is φ = 6557600.

The previous prime is 21640141. The next prime is 21640147. The reversal of 21640146 is 64104612.

It is not an unprimeable number, because it can be changed into a prime (21640141) 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, 163875 + ... + 164006.

It is an arithmetic number, because the mean of its divisors is an integer number (2950938).

Almost surely, 2^21640146 is an apocalyptic number.

21640146 is an abundant number, since it is smaller than the sum of its proper divisors (25574862).

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

21640146 is a wasteful number, since it uses less digits than its factorization.

21640146 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 327897.

The product of its (nonzero) digits is 1152, while the sum is 24.

The square root of 21640146 is about 4651.8970323944. The cubic root of 21640146 is about 278.6677614048.

Adding to 21640146 its reverse (64104612), we get a palindrome (85744758).

The spelling of 21640146 in words is "twenty-one million, six hundred forty thousand, one hundred forty-six".