20919090 has 16 divisors (see below), whose sum is σ = 50205888. Its totient is φ = 5578416.

The previous prime is 20919049. The next prime is 20919109. The reversal of 20919090 is 9091902.

It is a Harshad number since it is a multiple of its sum of digits (30), and also a Moran number because the ratio is a prime number: 697303 = 20919090 / (2 + 0 + 9 + 1 + 9 + 0 + 9 + 0).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 348622 + ... + 348681.

It is an arithmetic number, because the mean of its divisors is an integer number (3137868).

Almost surely, 2^20919090 is an apocalyptic number.

20919090 is an abundant number, since it is smaller than the sum of its proper divisors (29286798).

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

20919090 is a wasteful number, since it uses less digits than its factorization.

20919090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 697313.

The product of its (nonzero) digits is 1458, while the sum is 30.

The square root of 20919090 is about 4573.7391705256. The cubic root of 20919090 is about 275.5376369168.

The spelling of 20919090 in words is "twenty million, nine hundred nineteen thousand, ninety".