20691550 has 48 divisors (see below), whose sum is σ = 44474832. Its totient is φ = 7078400.

The previous prime is 20691509. The next prime is 20691569. The reversal of 20691550 is 5519602.

20691550 = T₇₀₅ + T₇₀₆ + ... + T₇₇₉.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8244 + ... + 10456.

It is an arithmetic number, because the mean of its divisors is an integer number (926559).

Almost surely, 2^20691550 is an apocalyptic number.

20691550 is an abundant number, since it is smaller than the sum of its proper divisors (23783282).

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

20691550 is a wasteful number, since it uses less digits than its factorization.

20691550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2253 (or 2248 counting only the distinct ones).

The product of its (nonzero) digits is 2700, while the sum is 28.

The square root of 20691550 is about 4548.7965441422. The cubic root of 20691550 is about 274.5349716504.

The spelling of 20691550 in words is "twenty million, six hundred ninety-one thousand, five hundred fifty".