21640662 has 16 divisors (see below), whose sum is σ = 48090480. Its totient is φ = 7213536.

The previous prime is 21640651. The next prime is 21640667. The reversal of 21640662 is 26604612.

It is a happy number.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21640667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 200323 + ... + 200430.

It is an arithmetic number, because the mean of its divisors is an integer number (3005655).

Almost surely, 2^21640662 is an apocalyptic number.

21640662 is an abundant number, since it is smaller than the sum of its proper divisors (26449818).

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

21640662 is a wasteful number, since it uses less digits than its factorization.

21640662 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 400764 (or 400758 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 21640662 is about 4651.9524933086. The cubic root of 21640662 is about 278.6699762916.

The spelling of 21640662 in words is "twenty-one million, six hundred forty thousand, six hundred sixty-two".