21148440 has 32 divisors (see below), whose sum is σ = 63445680. Its totient is φ = 5639552.

The previous prime is 21148427. The next prime is 21148481. The reversal of 21148440 is 4484112.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21148440.

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, 87999 + ... + 88238.

Almost surely, 2^21148440 is an apocalyptic number.

21148440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21148440 is an abundant number, since it is smaller than the sum of its proper divisors (42297240).

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

21148440 is a wasteful number, since it uses less digits than its factorization.

21148440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 176251 (or 176247 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 24.

The square root of 21148440 is about 4598.7433066002. The cubic root of 21148440 is about 276.5409470580.

The spelling of 21148440 in words is "twenty-one million, one hundred forty-eight thousand, four hundred forty".