20491900 has 72 divisors (see below), whose sum is σ = 52277904. Its totient is φ = 6873600.

The previous prime is 20491897. The next prime is 20491901. The reversal of 20491900 is 919402.

It is a super-2 number, since 2×20491900² = 839835931220000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20491901) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13584 + ... + 15016.

It is an arithmetic number, because the mean of its divisors is an integer number (726082).

Almost surely, 2^20491900 is an apocalyptic number.

20491900 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 20491900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26138952).

20491900 is an abundant number, since it is smaller than the sum of its proper divisors (31786004).

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

20491900 is a wasteful number, since it uses less digits than its factorization.

20491900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1471 (or 1464 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 20491900 is about 4526.7979853314. The cubic root of 20491900 is about 273.6491326500.

The spelling of 20491900 in words is "twenty million, four hundred ninety-one thousand, nine hundred".