21949640 has 32 divisors (see below), whose sum is σ = 50069880. Its totient is φ = 8658432.

The previous prime is 21949639. The next prime is 21949663. The reversal of 21949640 is 4694912.

It can be written as a sum of positive squares in 4 ways, for example, as 21362884 + 586756 = 4622^2 + 766^2 .

It is a super-2 number, since 2×21949640² = 963573392259200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21949640.

It is an unprimeable number.

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, 839 + ... + 6678.

Almost surely, 2^21949640 is an apocalyptic number.

21949640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21949640 is an abundant number, since it is smaller than the sum of its proper divisors (28120240).

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

21949640 is a wasteful number, since it uses less digits than its factorization.

21949640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7601 (or 7597 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 35.

The square root of 21949640 is about 4685.0442900788. The cubic root of 21949640 is about 279.9899656268.

The spelling of 21949640 in words is "twenty-one million, nine hundred forty-nine thousand, six hundred forty".