20961864 has 192 divisors, whose sum is σ = 74880000. Its totient is φ = 5132160.

The previous prime is 20961851. The next prime is 20961881. The reversal of 20961864 is 46816902.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 105237 + ... + 105435.

It is an arithmetic number, because the mean of its divisors is an integer number (390000).

Almost surely, 2^20961864 is an apocalyptic number.

20961864 is a gapful number since it is divisible by the number (24) 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 20961864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37440000).

20961864 is an abundant number, since it is smaller than the sum of its proper divisors (53918136).

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

20961864 is a wasteful number, since it uses less digits than its factorization.

20961864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 248 (or 241 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 20961864 is about 4578.4128254232. The cubic root of 20961864 is about 275.7253095644.

The spelling of 20961864 in words is "twenty million, nine hundred sixty-one thousand, eight hundred sixty-four".