21513400 has 48 divisors (see below), whose sum is σ = 50331600. Its totient is φ = 8551680.

The previous prime is 21513383. The next prime is 21513403. The reversal of 21513400 is 431512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21513403) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 52396 + ... + 52804.

It is an arithmetic number, because the mean of its divisors is an integer number (1048575).

Almost surely, 2^21513400 is an apocalyptic number.

21513400 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 21513400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25165800).

21513400 is an abundant number, since it is smaller than the sum of its proper divisors (28818200).

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

21513400 is a wasteful number, since it uses less digits than its factorization.

21513400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 688 (or 679 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21513400 is about 4638.2539818341. The cubic root of 21513400 is about 278.1226448481.

Adding to 21513400 its product of nonzero digits (120), we get a triangular number (21513520 = T₆₅₅₉).

Adding to 21513400 its reverse (431512), we get a palindrome (21944912).

It can be divided in two parts, 2151 and 3400, that multiplied together give a triangular number (7313400 = T₃₈₂₄).

The spelling of 21513400 in words is "twenty-one million, five hundred thirteen thousand, four hundred".