21522640 has 40 divisors (see below), whose sum is σ = 51771240. Its totient is φ = 8311296.

The previous prime is 21522619. The next prime is 21522671. The reversal of 21522640 is 4622512.

It can be written as a sum of positive squares in 4 ways, for example, as 5071504 + 16451136 = 2252^2 + 4056^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2319 + ... + 6958.

It is an arithmetic number, because the mean of its divisors is an integer number (1294281).

Almost surely, 2^21522640 is an apocalyptic number.

21522640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

21522640 is the 2320-th decagonal number.

It is an amenable number.

21522640 is an abundant number, since it is smaller than the sum of its proper divisors (30248600).

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

21522640 is a wasteful number, since it uses less digits than its factorization.

21522640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9319 (or 9313 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 22.

The square root of 21522640 is about 4639.2499393760. The cubic root of 21522640 is about 278.1624570180.

The spelling of 21522640 in words is "twenty-one million, five hundred twenty-two thousand, six hundred forty".