21513000 has 128 divisors (see below), whose sum is σ = 68739840. Its totient is φ = 5600000.

The previous prime is 21512969. The next prime is 21513001. The reversal of 21513000 is 31512.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is not an unprimeable number, because it can be changed into a prime (21513001) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 212950 + ... + 213050.

It is an arithmetic number, because the mean of its divisors is an integer number (537030).

Almost surely, 2^21513000 is an apocalyptic number.

21513000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21513000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34369920).

21513000 is an abundant number, since it is smaller than the sum of its proper divisors (47226840).

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

21513000 is a wasteful number, since it uses less digits than its factorization.

21513000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 196 (or 182 counting only the distinct ones).

The product of its (nonzero) digits is 30, while the sum is 12.

The square root of 21513000 is about 4638.2108619596. The cubic root of 21513000 is about 278.1209211202.

Adding to 21513000 its reverse (31512), we get a palindrome (21544512).

It can be divided in two parts, 2151 and 3000, that added together give a triangular number (5151 = T₁₀₁).

The spelling of 21513000 in words is "twenty-one million, five hundred thirteen thousand".