20649990 has 16 divisors (see below), whose sum is σ = 49560048. Its totient is φ = 5506656.

The previous prime is 20649983. The next prime is 20649991. The reversal of 20649990 is 9994602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20649991) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 344137 + ... + 344196.

It is an arithmetic number, because the mean of its divisors is an integer number (3097503).

Almost surely, 2^20649990 is an apocalyptic number.

20649990 is an abundant number, since it is smaller than the sum of its proper divisors (28910058).

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

20649990 is a wasteful number, since it uses less digits than its factorization.

20649990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 688343.

The product of its (nonzero) digits is 34992, while the sum is 39.

The square root of 20649990 is about 4544.2260067035. The cubic root of 20649990 is about 274.3510427693.

Subtracting from 20649990 its sum of digits (39), we obtain a triangular number (20649951 = T₆₄₂₆).

The spelling of 20649990 in words is "twenty million, six hundred forty-nine thousand, nine hundred ninety".