20961993 has 16 divisors (see below), whose sum is σ = 31409280. Its totient is φ = 12338304.

The previous prime is 20961961. The next prime is 20962013. The reversal of 20961993 is 39916902.

It is a happy number.

It is not a de Polignac number, because 20961993 - 2⁵ = 20961961 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (20961793) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10788 + ... + 12581.

It is an arithmetic number, because the mean of its divisors is an integer number (1963080).

Almost surely, 2^20961993 is an apocalyptic number.

20961993 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

20961993 is a deficient number, since it is larger than the sum of its proper divisors (10447287).

20961993 is a wasteful number, since it uses less digits than its factorization.

20961993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23408.

The product of its (nonzero) digits is 26244, while the sum is 39.

The square root of 20961993 is about 4578.4269132531. The cubic root of 20961993 is about 275.7258751707.

The spelling of 20961993 in words is "twenty million, nine hundred sixty-one thousand, nine hundred ninety-three".