21002480 has 40 divisors (see below), whose sum is σ = 51706512. Its totient is φ = 7906304.

The previous prime is 21002479. The next prime is 21002503. The reversal of 21002480 is 8420012.

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

It is a super-2 number, since 2×21002480² = 882208332300800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (17).

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, 6362 + ... + 9081.

Almost surely, 2^21002480 is an apocalyptic number.

21002480 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21002480 is an abundant number, since it is smaller than the sum of its proper divisors (30704032).

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

21002480 is a wasteful number, since it uses less digits than its factorization.

21002480 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15473 (or 15467 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 17.

The square root of 21002480 is about 4582.8462771514. The cubic root of 21002480 is about 275.9032777375.

Adding to 21002480 its reverse (8420012), we get a palindrome (29422492).

The spelling of 21002480 in words is "twenty-one million, two thousand, four hundred eighty".