21149640 has 64 divisors (see below), whose sum is σ = 70502400. Its totient is φ = 5639616.

The previous prime is 21149629. The next prime is 21149659. The reversal of 21149640 is 4694112.

21149640 is a `hidden beast` number, since 2 + 1 + 14 + 9 + 640 = 666.

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

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8712 + ... + 10871.

It is an arithmetic number, because the mean of its divisors is an integer number (1101600).

Almost surely, 2^21149640 is an apocalyptic number.

21149640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21149640 is an abundant number, since it is smaller than the sum of its proper divisors (49352760).

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

21149640 is a wasteful number, since it uses less digits than its factorization.

21149640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19603 (or 19593 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21149640 is about 4598.8737751758. The cubic root of 21149640 is about 276.5461774337.

The spelling of 21149640 in words is "twenty-one million, one hundred forty-nine thousand, six hundred forty".