20981400 has 216 divisors, whose sum is σ = 75945660. Its totient is φ = 4787200.

The previous prime is 20981399. The next prime is 20981407. The reversal of 20981400 is 418902.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20981407) by changing a digit.

It is a polite number, since it can be written in 53 ways as a sum of consecutive naturals, for example, 1234192 + ... + 1234208.

Almost surely, 2^20981400 is an apocalyptic number.

20981400 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 20981400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37972830).

20981400 is an abundant number, since it is smaller than the sum of its proper divisors (54964260).

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

20981400 is a wasteful number, since it uses less digits than its factorization.

20981400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75 (or 38 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 24.

The square root of 20981400 is about 4580.5458190045. The cubic root of 20981400 is about 275.8109396261.

Multiplying 20981400 by its sum of digits (24), we get a square (503553600 = 22440²).

20981400 divided by its sum of digits (24) gives a square (874225 = 935²).

The spelling of 20981400 in words is "twenty million, nine hundred eighty-one thousand, four hundred".