20951091 has 48 divisors (see below), whose sum is σ = 38039040. Its totient is φ = 10834560.

The previous prime is 20951087. The next prime is 20951107. The reversal of 20951091 is 19015902.

It is a happy number.

It is not a de Polignac number, because 20951091 - 2² = 20951087 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20951011) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 27151 + ... + 27911.

It is an arithmetic number, because the mean of its divisors is an integer number (792480).

Almost surely, 2^20951091 is an apocalyptic number.

20951091 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

20951091 is a deficient number, since it is larger than the sum of its proper divisors (17087949).

20951091 is a wasteful number, since it uses less digits than its factorization.

20951091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 816 (or 813 counting only the distinct ones).

The product of its (nonzero) digits is 810, while the sum is 27.

The square root of 20951091 is about 4577.2361748112. The cubic root of 20951091 is about 275.6780666639.

Adding to 20951091 its reverse (19015902), we get a palindrome (39966993).

The spelling of 20951091 in words is "twenty million, nine hundred fifty-one thousand, ninety-one".