21510140 has 12 divisors (see below), whose sum is σ = 45171336. Its totient is φ = 8604048.

The previous prime is 21510133. The next prime is 21510157. The reversal of 21510140 is 4101512.

It is a super-2 number, since 2×21510140² = 925372245639200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 537734 + ... + 537773.

It is an arithmetic number, because the mean of its divisors is an integer number (3764278).

Almost surely, 2^21510140 is an apocalyptic number.

21510140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21510140 is an abundant number, since it is smaller than the sum of its proper divisors (23661196).

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

21510140 is a wasteful number, since it uses less digits than its factorization.

21510140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1075516 (or 1075514 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 21510140 is about 4637.9025431762. The cubic root of 21510140 is about 278.1085958426.

Adding to 21510140 its reverse (4101512), we get a palindrome (25611652).

The spelling of 21510140 in words is "twenty-one million, five hundred ten thousand, one hundred forty".